Tabulae, 257, 345, 385, 387

Tail-like appendages, of certain Ciliata, 141 n.;

(spine) of _Caenomorpha uniserialis_, 154, 155

_Tamoya punctata_, _319_

Tan-pits infested by _Fuligo varians_, 92

Tapeworms, nutrition of, 38;

alternation of generations in, 44

_Tarsaster_, _474_

_Tealia_ = _Urticina_, _q.v._

_Tedania_, 223

Tegmen, of Crinoidea, 580;

of _Antedon rosacea_, 581, 585;

of _Hyocrinus_, 590;

of Articulata, 595;

of Camerata, 595

Telestidae, _348_

_Telesto_, 346, _348_;

_T. prolifera_, 347;

_T. rubra_, 336, 347

Telolecithal (= segmentation limited to one region of the oosperm owing

to excess of yolk), 133 n.

Telosporidia, _97_ f.

Temnopleurinae, _539_

Temperature, in relation to protoplasmic movements, 7;

to breeding, 47;

to fission of Ciliates, 148;

changes of, stimulus of, 19, 22;

maximum (Dallinger and Drysdale's experiments), 118

Tension, surface-, 17, 34

Tentacles, of _Actinobolus_ and _Ileonema_, 152;

of Suctoria, 158 f., 160, 162;

of Hydrozoa, 251 f.;

of Scyphozoa, 311 f.;

of Anthozoa, 327;

of Alcyonaria, 331 f.;

of Zoantharia, 366 f.;

of Ctenophora, 414 f.;

of Holothuroidea, 561 f.;

of Pelmatozoa (= podia), 579 f.

Tentacle-scale, of _Ophiothrix fragilis_, 480

Tentacular (= transverse) plane, 414

Tentaculata, _417_

Tentaculifera (= Suctoria), _159_ f., 160, 162

Tentaculozooids, 265

Tentilla, 299

Termites, Trichonymphidae parasitic in, 123

Terrestrial Protozoa, 48

Tertian fever, a parasitic disease, 104 f.

_Tessera_, 320, _321_

Test, classificatory value of, 51 n.;

of _Euglypha_, 29;

of Rhizopoda, 29, 53, 54, 55;

of _Trichosphaerium sieboldii_, 54;

of _Arcella vulgaris_, 55;

of _Diffugia pyriformis_, 55;

of _Hyalosphenia lata_, 55;

of _Quadrula symmetrica_, 55;

of Foraminifera, 58 f., 61, 63, 65, 67, 68, 69;

of Allogromidiaceae, 60;

of _Microgromia socialis_, 60;

of _Lieberkühnia_, 61;

of marine Foraminifera, 62 f.;

of _Discorbina_, 63;

of _Frondicularia_, 63;

of _Globigerina_, 63;

of _Lagena_, 63;

of _Nodosaria_, 63;

of _Nummulites_, 63;

of _Planorbulina_, 63;

of _Saccammina_, 63;

of _Spiroloculina_, 63;

of _Allogromia_, 65;

of _Miliola_, 65;

of _Quinqueloculina_, 65, 67;

of _Rotalia_, 65;

of _Squamulina_, 65;

of _Biloculina_, 67;

(gelatinous) of _Nuclearia_, 74;

of Chrysomonadaceae, 110, 113 f.;

(chitinous) of Tintinnidae, 152, 155

—see also Shell, Skeleton, Theca

_Tethya_, 211, _218_, 222;

gemmule, 230;

scleroblasts, 233, 233;

_T. lyncurium_, 218

_Tetilla_, 212, _213_, 218, 233;

_T. casula_, 212;

_T. pedifera_, 211, 213

Tetracoralla, 394

Tetracrepid, 215—see Rhabdocrepid

Tetractinellida, _211_ f., 218, 231

_Tetramitus_, _111_, 119;

_T. rostratus_, gametes of, 116 n.

Texas fever, 120 f.

_Textularia_, _59_;

in chalk, 70, 242

Textulariaceae, _59_

Thalassianthidae, _383_

_Thalassicolla_, _77_, 83;

_T. nucleata_, regeneration, 79 n.

_Thalassophysa_, _77_;

reproduction, 86 n.

_Thamnograptus_, _281_

_Thamnostylus_, _270_

_Thaumactis_, _382_

_Thaumantias_, _278_

Thaumantiidae, _278_

_Thaumatocrinus_, 588, 589, _594_

_Thaumatomastix_, _110_

Theca, of Flagellata, 112 f.;

of _Dinobryon_, 112;

(branched) of _Rhipidodendron_, 112;

(stalked) of _Diplomita_, 112;

of _Salpingoeca_, 122;

of _Acineta_, 159, 160;

of Corals, 370

—see also Shell, Skeleton, Test

Thecamoebae, 51 n.

Thecidae, _346_

_Thecocarpus_ (Plumulariidae, _279_), 276

_Thecocystis_, _596_, 596

Thecoidea, _580_, _596_

Thélohan, on Sporozoa, 94

_Thenea wyvillei_, _212_

_Theoconus_, _79_, 80

Thermotaxy, 22

Thigmotaxy, 20

Thomson, Wyville, on _Calcaromma_, 83

Thorax = second chamber of Monaxonic Radiolarian shell, 84

_Thyone_, _573_

_Tiara_, _273_

Tiarechinidae, _557_

_Tiarechinus_, _557_

Tiaridae, _273_

Tick, intermediate host of _Karyolysus_, 102;

of _Piroplasma_, 120;

of _Treponema_, 121 n.;

Persian, 120;

Zambezian, 121 n.

Tick fever, 120

Tiedemann's bodies, 442, 444, 458;

represented by so-called Polian vesicles of _Echinus esculentus_, 516

Tinctin bodies, 161

_Tinerfe_, _417_

Tintinnidae, _155_;

tests of, 152

_Tintinnus_, _137_

Tissues (definition), 3

Tolerance, induced, of a higher temperature, 118

Tone, 519

Tooth, of _Ophiothrix fragilis_, 482;

of _Echinus esculentus_, 505, 524, 525;

of _Echinarachnius parma_, 546

Tooth-papilla, of _Ophiothrix fragilis_, 482;

of _Ophiocoma_, 493;

of Ophiocomidae, 499

Topsent, 196, 218 n.

Tornaria, 616

_Torquatella typica_ (= _Strombidium_), 155 n.

Torus angularis, of _Ophiothrix fragilis_, 482

Toxa (= a bow-shaped spicule without spiral twist), 222

Toxaspire (a spiral rod in which the twist a little exceeds a single

revolution. The pitch of the spiral being great the spicule appears

bow-shaped), 222

Trabeculae, traversing ampullae of tube-feet of _Echinus esculentus_,

517;

traversing coelom of _Echinarachnius parma_, 545;

traversing coelom of _Antedon rosacea_, 585

Tracheae of Chondrophoridae, 309

_Trachelius_, _137_, 152 n.;

_T. ovum_, 153;

endosarc of, 144

_Trachelomonas_, _110_, 112;

galvanotaxy of, 22

Trachomedusae, _288_ f.

_Trachynema_, _294_;

_T. funerarium_, 294

Trachynemidae, _294_

Tractellum, 18, 114

_Tragosia_, 224

Transverse fission, of Flagellata, 109 f.;

of Dinoflagellata, 110, 131;

of _Polykrikos_, 131;

of Ciliata, 147;

of Suctoria, 161

Transverse flagellum and groove, in Dinoflagellata, 110, 130 f.;

multiple, in _Polykrikos_, 132

Transverse (= tentacular) plane, 414

Transverse section, of the arm of an Asteroid, 443;

of the arm of an Ophiuroid, 480;

of the radius of an Echinoid, 518;

of the radius of a Holothuroid, 562;

of body of a Holothuroid, 563;

of arm of _Antedon_, 586

Trembley, 254, 255

Trepang, 571

_Treponema_, _111_, 121;

_T. obermeieri_, 121;

_T. pallidum_, 121;

_T. zeemannii_, 120

Triaene, 183, 224, 233

Triaxon, 184

_Trichaster_, _501_

Trichasteridae, _501_

Trichites (hair-like spicules often occurring in sheaves or clusters),

234

Trichocysts, 142 f.;

of Chloromonadaceae, 113 n.;

Mitrophanow on, 142 n.;

adoral, of Gymnostomaceae, 145

_Trichodina_, _138_, 158

Trichodragmata (a sheaf of straight spicules of hair-like fineness), 222

_Trichogorgia_, _355_

_Trichomonas_, _111_, 115;

conjugation, 116 n.;

_T. vaginalis_, 119

_Trichonympha_, _111_

Trichonymphidae, _111_, 123 f.;

flagella, 114

_Trichosphaerium_, _51_, 53 f.;

test, 53;

life-cycle, 54, 56

_Trichostemma_, _216_

Trichostomata, _137_

Tridactyle pedicellariae, of _Echinus esculentus_, 506, 507;

of _E. acutus_, 509;

of _E. elegans_, 510;

of _Echinarachnius parma_, 544

Trifoliate pedicellariae, of _Echinus esculentus_, 507, 508;

of _E. acutus_, 509;

of _E. alexandri_, 510;

of _Echinocardium cordatum_, 550;

absent in Cidaridae, 534

_Trigonocidaris arbacina_, _539_

_Triloculina_, _59_, 66

Trimastigidae, _111_, 112

_Tripedalia cystophora_, _319_

Tripedaliidae, _319_

Triplechinoid type of ambulacral plate, 531, 539

Tripod, 83;

-shaped spicule of Radiolaria, 76

Tripolis, 87

Tripylaea, _76_

Trivium, of _Echinarachnius parma_, 543;

of _Holothuria nigra_, 561

_Trochammina_, _59_

_Trochocyathus_, _399_;

_T. hastatus_, 398

_Trochocystis_, _597_;

_T. bohemicus_, 597

_Trochoderma_, _577_

_Trochodota_, _577_

_Trochosmilia_, _401_

_Trochostoma_, _575_;

_T. violaceum_, 575

Trophodisc, 284

Trophozooid, 388

Tropical Africa, Trypanosomic diseases of, 119 f.

Trout, black-spotted, destroyed by _Hydra_, 256 n.

_Trypanosoma_, _111_, 115 f., 119 f., 120;

podoplast or blepharoplast of, 19 n., 109 n.;

undulating membrane of, 115;

_Halteridium_, a supposed state of, 103 n., 120;

affinities to Acystosporidae, 106;

morphology of, 120, 121;

_T. brucei_ infests hoofed quadrupeds, 119;

_T. evansii_ causes Surra disease in Ruminants, 119;

_T. gambiense_, cause of sleeping-sickness, 120;

_T. lewisii_, infests Rodents, 119;

_T. noctuae_, 120;

conjugation in, 116 n.

Trypanosomoid character of blasts of Acystosporidae, 106

Tsetse Flies, intermediate hosts of Trypanosomes of Nagana and

sleeping-sickness, 119 f.

Tube, of _Phalansterium_, 113;

of certain Ciliates, 152;

of _Maryna socialis_, 152;

of _Schizotricha socialis_, 152;

of _Stentor_, 154;

of Vorticellidae, 158;

fertilising in _Chlamydomonas_, 125

Tube-foot, 428;

of _Asterias rubens_, 441 f.;

of _Echinus esculentus_, 517 f.;

of Endocyclica, 532;

of Arbaciidae, 532;

of Cidaridae, 532;

of Diadematidae, 532;

of Echinothuriidae, 532;

of _Echinocardium cordatum_, 551;

of _Echinarachnius parma_, 545, 546, 547;

of _Palaeodiscus_, 557;

of _Holothuria nigra_, 561

_Tubipora_, 329, 336, 343, _344_;

_T. musica_, 338, 343

Tubiporidae, _344_

_Tubularia_, 268, _271_;

_T. larynx_, 263;

_T. parasitica_, 268

Tubulariidae, _271_

Tumour, malignant, associated with _Leydenia_, 91

Tunicata, 621

Tuning-fork, 192, 193

Turbellaria, fresh-water, distribution of, 48;

symbiotic with _Zoochlorella_, 126

_Turbinaria_, _396_

_Turbinolia_, _399_

Turbinoliidae, _398_

_Turritopsis_, _273_, 295

_Tuscarora_, _79_, 85

Tylostyle (a style in which a knob surrounds the origin), 224

Tylote, 183, 224

Tylotoxea (a rhabdus of which one actine is tylote or knobbed, the other

oxeate, the latter directed towards the surface of the Sponge), 224

Tyrosin, 15

Uexküll, on function of pedicellariae of _Echinus_, 508;

on physiology of nervous system of Echinoidea, 519;

on vision of Echinoidea, 522;

on respiratory function of Aristotle's lantern, 527;

on pedicellariae of _Sphaerechinus_, 541

_Uintacrinus_, 588

Ulmaridae, _324_

_Ulmaris_, 314, _324_;

_U. prototypus_, 315, 324

_Umbellula_, 331, 359, 360, _363_;

_U. gracilis_, 359

Umbellulidae, _362_

Umbrella of Medusae, 251

Uncinataria, _203_

Under arm-plate of Ophiuroidea, 491

Under basal-plate of Crinoidea—see Infra-basal plate

Undulating membrane, of Flagellata, 111, 115, 123;

of _Trypanosoma_, 121;

of _Dinenympha_, 123;

of _Stylonychia mytilus_, 139 f.;

of Ciliata Trichostomata, 137 f., 145;

of _Glaucoma_, 153;

of _Pleuronema chrysalis_, 153, 154;

of _Caenomorpha uniserialis_, 155;

of _Vorticella_, 156, 157

Unequal fission in _Spirochona_, 147

Upper arm-plate, of Ophiuroidea, 491;

of _Ophioteresis_, 491;

absent in Cladophiurae, 491, 500

_Urechinidae_, _554_ n.

Urine, 13

_Urocentrum_, _137_, 141 n.

_Uronema_, _137_, 141 n.

_Urticina_, 379, _382_;

_U. crassicornis_, 379, 382

Ussov, 257 n.

_Ute_, 189, 190, _192_, 221

Vacuole, 5 f.;

of _Collozoum inerme_, 76;

of _Oikomonas_, 112;

contractile or pulsatile, 14 f.—see Contractile vacuole;

formative, 14 f.—see Alveole, Food-vacuole, Formative vacuole,

Ingestion, vacuole of

_Vaginicola_, _138_, 158

Valvata, _461_, _471_ f.

Valvate, pedicellariae, of Antheneidae, 456, 471

_Vampyrella_, _89_

Vaney, 292 n.

Variation in character of Foraminiferal shell at different stages of

growth, 66

Vegetative, growth, in coloured Flagellates, 115;

rest, 37

Velata, _461_, _464_ f., 466

_Velella_, 301, 302, _309_;

_V. spirans_, 304

Veley, Lilian, on _Pelomyxa_, 53 n.

_Ventriculites_, 208, 208

Venus's Flower-basket (= _Euplectella aspergillum_), 197

Venus's girdle, 420

Veretilleae, _364_

_Veretillum_, _364_

Vermicles, of Gaule, a name for _Lankesterella_, 102

Verrucae, 331

_Verrucella_, _357_;

_V. guadaloupensis_, 357

Vertebra, of Ophiuroidea, 481, 491;

of Streptophiurae, 491, 494;

of _Ophioteresis_, 481, 491;

of _Ophiohelus_, 491, 493;

of Zygophiurae, 491;

of _Ophiothrix fragilis_, 480;

of _Ophiarachna_, 481;

of Cladophiurae, 491, 500;

of _Astroschema_, 481;

of _Gorgonocephalus_, 491;

of _Astrophyton_, 491;

of fossil Ophiuroidea, 501, 502

Vertebrates, cold-blooded, hosts of Haemosporidae, 102

Verticilladeae, _363_

Verworn, on general physiology and protoplasm, 3 n.;

on protoplasmic movements, 16 n., 17;

on regeneration, 35 n.;

of _Thalassicolla nucleata_, 79 n.

Vesicular nucleus, 25

Vestibule, of Peritrichaceae, 145;

of _Carchesium_, 146;

of _Vorticella_, 156, 157

_Vexillum_, _421_

Vibratile styles of Rotifers, 141

_Villogorgia_, _356_

_Virgularia_, 339, _362_;

_V. juncea_, 360;

_V. mirabilis_, 362;

_V. rumphii_, 330, 360

Virgulariidae, _362_

Vision, of Asteroidea, 446;

of Echinoidea, 522

Vital forces, 12 f.;

processes, 11 f.

Vitreous Foraminifera, _58_, 62

Voluntary muscles of Mammals infested by Sarcosporidiaceae, 108

Volvocaceae, _110_, _111_, 125 f.;

literature of, 119

Volvocidae, _111_, 126 f., 127, 129;

theca, 113

_Volvox_, plasmic cell connexions of, 37 n.;

a true vegetable Protist, 130;

_V. globator_, 127 f.

_Vorticella_, _138_, 155 f., 157;

_V. sertulariae_, symbiotic _Zooxanthella_ in, 125

Vorticellidae, 157 f.;

fission, 158;

colonies, 158

Vosmaer, 187 n., 212, 234 n., 237

Wager, on Euglenaceae, 125

Wagner, 256 n.

Wallich, on Protozoa, 45

_Walteria_, 199, _202_;

_W. flemmingi_, 206;

_W. leuckarti_, 206

Wasielewski, on Sporozoa, 94 n.

Water in protoplasm, 12

Water-Fleas, Vorticellidae found on, 158;

rheotaxy of (small Crustacea), 21

Water-vascular system, 428;

of _Asterias rubens_, 441;

of Asteroidea, 457;

of _Ophiothrix fragilis_, 486;

of _Echinus esculentus_, 516;

of _Echinarachnius parma_, 546;

of _Echinocardium cordatum_, 551;

of _Holothuria nigra_, 564;

of Holothuroidea, 568;

of Synaptida, 568;

of Molpadiida, 568;

of Elasipoda, 568;

of _Psolus_, 569;

of _Antedon rosacea_, 583;

of Carpoidea, 597

Weltner, 177, 178

White Ants, hosts of Trichonymphidae, 123

White Man's Grave, 106

Wille, on Volvocaceae, 119

Willey, 194 n., 248, 421, 422

Williams, on density of living protoplasm, 13 n.

Williamson, on structure of Foraminifera, 62

Wilson, on protoplasm, 3 n.;

on syngamy, 34 n.

Wilson, on Sponges, 171, 231

Woltereck, 302

Wolters, on reproduction of _Monocystis_, 96 n.

Woodcock, on association and conjugation in Gregarines, 99 n.;

on Haemoflagellates (= Trypanosomidae), 119 n.

Worms, Earth-, hosts of _Monocystis_, 95

Wreath, adoral, peristomial, of cilia or membranellae of Ciliata

Trichostomata, 137 f.;

of _Stylonychia mytilus_, 139 f.;

of _Metopus_, 154;

of _Caenomorpha uniserialis_, 155;

of Vorticella, 156, 157;

posterior, of _Vorticella_, 156, 157

_Wrightella_, _351_

Wrisburg, on organisms of putrefaction, 43

Würmchen, of Gaule, a name for _Lankesterella_, 102

_Xenaster_, _476_

_Xenia_, 331, 335, 346, _348_

Xeniidae, _348_

_Xenospongia patelliformis_, _216_

_Xiphacantha_, _78_, 78

_Xiphigorgia_, _357_

Yaws, 121 n.

Yellow-cells (= _Zooxanthella_), 80, 86, 125, 261, 373, 396

Yolk-granules of ovum of Sea-urchin, 7

Young state of _one_ pairing-nucleus essential, 34

_Yvesia_, 224

Zambezian Tick, infects man with _Treponema_, 121 n.

Zaphrentidae, _406_

_Zaphrentis_, _407_

Zederbauer, on syngamy in Dinoflagellates, 131 n.

Zittel, 241 n.

Zoantharia, _329_, _365_ f.;

age, 375;

food, 373;

form, 366;

gonads, 369;

mesenteries, 366 f., 368;

mesenteric filaments, 369;

reproduction, 371;

skeleton, 370;

stomodaeum, 369;

tentacles, 366

Zoanthidae, _404_

Zoanthidea, 370, _404_ f.

_Zoanthus_, _405_;

_Z. macgillivrayi_, 406;

_Z. sulcatus_, 406

Zonarial Radiolaria, 75

_Zoochlorella_, _111_;

a Chlamydomonad, 126;

symbiotic, in Heliozoa, 73;

in _Paramecium bursaria_, 153;

in _Stentor polymorphus_, 154;

in _Ophrydium_, 158;

in _Ephydatia_, 175;

in _Hydra viridis_ (= chlorophyll corpuscles), 256

Zooids of _Volvox globator_, 127

Zoosporeae, _89_

Zoospores, of Algae and Fungi, possess contractile vacuole, 15;

of Lower Plants, 17 f.;

of Sarcodina, 49;

of _Trichosphaerium_, 54;

of _Microgromia socialis_, 60;

of Foraminifera, 67 f.;

of _Clathrulina_, 73;

of Radiolaria, 85 f.;

of _Zooxanthella_, 86;

of Acrasieae, 90;

of _Didymium_, 92;

of _Paramoeba eilhardii_, 116 n.

_Zoothamnium_, _138_, 158

_Zooxanthella_, _110_;

a Chrysomonad, 125;

in Radiolaria, 80, 86;

in _Vorticella sertulariae_, 125;

in _Millepora_, 261;

in Zoantharia, 373 f.;

in Madrepores, 396

Zopf, on Monadineae (Flagellates and Proteomyxa), 40

_Zoroaster_, _474_

Zoroasteridae, 454, _474_

_Zostera_, 422

Zygophiurae, 491, _494_, _495_ f., 502

_Zygophylax_, _280_

Zygote, 37 f.;

_Amoeba coli_, 57;

_Centropyxis aculeata_, 57;

_Chlamydophrys stercorea_, 57;

Foraminifera, 69;

_Actinophrys sol_, 72;

_Actinosphaerium_, 75;

Gregarinidaceae, 95 f., 97;

Coccidiaceae, 97, 100 f.;

_Coccidium_, 100, 101 f.;

Acystosporidae, 97, 104 f.;

Flagellata, 116 n., 117 f.;

_Bodo saltans_, 117 f.;

Dinoflagellata, 131 n.;

Ciliata, 148 f.

—see also Coupled cell, Fertilised egg, Ookinete, Oosperm, Oospore,

Zygotospore

Zygotoblasts of Acystosporidae, 104 f.

Zygotomeres (= naked spores of Acystosporidae), 104 f.

Zygotonucleus (= Fusion-nucleus, a nucleus formed by fusion of two

gametonuclei), 33 f.

Zygotospore (= resting zygote), 97

Zykoff, 178

Zymase (= chemical ferment), 15;

in relation to brood-division, 32 f.

END OF VOL. I

_Printed by_ R. & R. CLARK, LIMITED, _Edinburgh_.

[1] For detailed studies of protoplasm see Delage, _Hérédité_, 2nd ed.

1903; Henneguy, _Leçons sur la Cellule_, 1896; Verworn, _General

Physiology_, English ed. 1899; Wilson, _The Cell in Development and

Inheritance_, 2nd ed. 1900. All these books contain full

bibliographies.

[2] As we shall see later, it is by no means easy to separate sharply

Protozoa and Protophyta, the lowest animals and the lowest plants;

and therefore in our preliminary survey to designate lowly forms of

life, not formed of the aggregation of differentiated cells, we shall

employ the useful term "Protista," introduced by Haeckel to designate

such beings at large, without reference to this difficult problem of

separation into animals and plants (see also p. 35 f.).

[3] The "micron," represented by the Greek letter µ, is 1/1000 mm., very

nearly 1/25,000 of an inch, and is the unit of length commonly

adopted for microscopic measurements.

[4] A solid substratum is required, to which the lower surface adheres

slightly: that movement is complicated by a sort of rolling over of

the upper surface, constantly prolonging the front of the

pseudopodium, while the material of the lower surface is brought up

behind. H. S. Jennings, _Contr. to the Study and Behaviour of the

Lower Organisms_, 1904, pt. vi. p. 129 f., "The Movements and

Reactions of Amoeba."

[5] If the protoplasm contains visible granules, as it usually does,

within a clear external layer, we see that these stream constantly

forwards along the central axis of each process as it forms, and

backwards just within the clear layer all round, like a fountain

playing in a bell-jar. This motion is most marked when a new

pseudopodium is put forth, and ceases when it has attained full

dimensions.

[6] We use as a corresponding adjective the term "plasmic."

[7] For the study of the structure of protoplasm under the microscope it

is necessary to examine it in very thin layers, such as can for the

most part be obtained only by mechanical methods (section-cutting,

etc.). These methods, again, can only be applied to fixed specimens,

for natural death is followed by rapid changes, and notably by

softening, which makes the tissue less suitable for our methods. We

further bring out and make obvious pre-existing differentiations of

our specimens by various methods of staining with such dyes as

logwood and cochineal and their derivatives, and coal-tar pigments

(see also p. 11 n.).

[8] In many Protista these granules have been shown by Schewiakoff, in

_Z. wiss. Zool._ lvii. 1893, p. 32, to consist of a calcium

phosphate, probably Ca_{3}P_{2}O_{8}.

[9] It is not always possible to tell how much of these structures

represents what existed in life (see p. 11).

[10] The chromatin and nucleoles are especially rich in phosphorus,

probably in the combination nucleinic acid.

[11] In chemical phrase the process is "exothermic."

[12] The growth of crystals is a mere superficial deposit, and cannot at

all be identified with protoplasmic growth.

[13] A. Bolles Lee, in his _Microtomist's Vade Mecum_, 1st ed. (1885),

pointed out that "Clearing reagents are liquids whose primary

function is to make microscopic preparations transparent by

penetrating amongst the highly refractive elements of which the

tissues are composed, having an index of refraction not greatly

inferior to that of the tissues to be cleared" (p. 213). We showed

later ("The State in which Water exists in Live Protoplasm," in _Rep.

Brit. Ass._ 1889, p. 645, and _Journ. Roy. Micr. Soc._ 1890, p. 441)

that since the refractivity of living protoplasm is only 1.363-1.368,

it follows that the water in the living protoplasm is in a state of

perfect physical combination, like the water of a solution of gum

[read a "mucilage"] or of a jelly. Now the phenomena of protoplasmic

motions as studied in the Rhizopoda and in the vegetable cell, seem

absolutely to preclude the jelly supposition, and for these cases we

must admit that living protoplasm is a viscid liquid whose

refractivity is probably the mean of the two constituents separated

by death, the one solid, the other a watery solution: and death is

for us essentially a process of precipitation (or better,

"desolution"). For further work on these lines see Hardy in _Journ.

Physiol._ vol. xxiv. 1899, p. 158, and Fischer, _Fixirung u.

Färbung_, 1900.

[14] In its original use "automatism" designates the continuous sequence

and combination of actions, without external interference, performed

by complex machines designed and made for specific ends by

intelligent beings: thus we speak correctly of "automatic ball

bearings" that tighten of themselves when they become loose; but even

these cannot take up fresh steel and redeposit it, either to replace

the worn parts or to strengthen a tube that is bending under a

stress.

[15] Proteids are organic compounds containing carbon, hydrogen, nitrogen,

and oxygen, of which white of egg (albumen) is a familiar type.

Nucleo-proteids are compounds of proteids with nucleinic acid, which

in addition to the above elements contain phosphorus.

[16] The specific gravity of living protoplasm has been estimated by

determining the density of a solution of gum in which certain

Infusoria float freely at any depth. It was found by the concurrent

results of Julia B. Platt and Stephen R. Williams (see _Amer.

Natural._ xxxiii. 1899, p. 31, xxxiv. 1900, p. 95) to be from 1.014

to 1.019, while the Metazoon _Hydra_ was found to give a density of

only 1.0095 to 1.0115. The difference of about 0.006, it is easy to

show, is of the correct "order of magnitude," if we admit that the

actual substance of the Hydra has about the same specific gravity as

the Infusorian, while the density of the whole is lightened by the

watery contents of the internal cavity, etc. Jensen obtained a much

higher result for _Paramecium_, using a solution of the crystalloid

substance, potassium carbonate; but it is almost certain that this

would be readily absorbed by the organism, and so raise its density

in the course of the experiment.

[17] Energy may be derived from the mere _splitting up_ of complex

substances within the cell: when such a splitting involves the

liberation of CO_{2} the process is (mis-)called "intramolecular

respiration."

[18] A similar organ, but with _cellular_ walls, is the bladder of the

Rotifers and certain Platyhelminthes, in connexion with their renal

system (vol. ii. pp. 53, 199, and especially pp. 213-5).

[19] In _Rep. Brit. Ass._ 1888, p. 714; _Ann. Mag. Nat. Hist._ (6), iii.

1889, p. 64. This view has been fully worked out, mainly on Ciliates,

by Degen in _Bot. Zeit._ lxiii. Abt. 1. 1905.

[20] See Hartog, "On Multiple Cell-division, as compared with Bi-partition

as Herbert Spencer's limit of growth," in _Rep. Brit. Ass._ 1896, p.

833; "On a Peptic Zymase in Young Embryos," _ibid._ 1900, p. 786;

"Some Problems of Reproduction," ii. _Quart. Journ. Micr. Sci._

xlvii. 1904, p. 583.

[21] "On the Digestive Ferment of a large Protozoon." _Rep. Brit. Ass._

1893, p. 801.

[22] See for studies of the movements of Protoplasm, Berthold,

_Protoplasmamechanik_ (1886); Bütschli, _Investigations on

Microscopic Foams and on Protoplasm_, English ed. 1894; Verworn,

_General Physiology_, 1899; Le Dantec, _La Matière Vivante_, 1893?;

and Jensen, "Unters. ueb. Protoplasmamechanik," in _Arch. Ges. Phys._

lxxxvii. 1901, p. 361; Davenport, _Experimental Morphology_, i. 1897;

H. S. Jennings, _Contr._ etc. 1904.

[23] The terms "expansion" and "contraction" refer only to the

_superficial area_: it is very doubtful whether the _volume_ alters

during these changes.

[24] For discussions on the mechanism of ciliary action, see Schäfer,

_Anat. Anz._ xxiv. 1904, p. 497, xxvi. 1905, p. 517; Schuberg, _Arch.

Protist._ vi. 1905, p. 85.

[25] Like the line of most rapid growth in a circumnutating plant-stem.

[26] A similar body lies at the centre to which the axial filaments of the

radiating pseudopodia of the Heliozoa converge, and might be termed

by parity a "podoplast"; but "centrosome" is a convenient general

term to include all such bodies. It is clearly of nuclear origin in

_Trypanosoma_ (Fig. 39, p. 120).

[27] See for development of this view W. M'Dougall in _Journ. Anal.

Physiol._ xxxi. 1897, pp. 410, 539. I put it forward in the first

draft of this essay in 1894.

[28] The best general account is to be found in Davenport, _Experimental

Morphology_, 1897.

[29] See Jennings in _Woods Holl. Biol. Lect._ 1899, p. 93.

[30] It is not always easy to distinguish these two classes of phenomena.

[31] Jennings, in his studies on _Reactions to Stimuli in Unicellular

Organisms_ (1899-1900), has shown that whatever be the nature of the

repellent stimulus, chemical or mechanical or thermal, the reaction

of _Paramecium_ and many other Protista is always the same. It swims

backward a short distance, turns towards the aboral surface, and then

having thus reversed swims on again in the new direction, front

foremost as before. Apparent "positive taxies" are often really

negative ones; for if the _Paramecium_ be placed in water containing

CO_{2} it shows the reaction not on entering the part charged with

this acid, but on passing away from it into purer water, so that it

continually tends to turn back into the acid part, while within it or

in the water at a distance not yet charged it swims about

irregularly. It appears due to this that the individuals become

aggregated together, as they excrete this gas into the water. If a

repellent substance diffuse towards the hinder end of a _Paramecium_,

the response, instead of carrying it away, brings it into the region

of greater concentration, and may thus kill it.

[32] "Galvanotaxis and Chemotaxis," _Journ. of Physiol._ vol. xxvi.

1900-1901, p. 291.

[33] Let us take the case of a 1-centimetre cube, growing to the size of a

2-centimetre cube. The superficial area of the 1 cm. cube measures 6

square centimetres, and its bulk is 1 cubic centimetre. The

superficial area of the 2-centimetre cube measures 24 square

centimetres, while its volume measures 8 cubic centimetres. Thus the

larger cube has only 3 cm. sq. of surface to every cubic cm. of

volume, instead of 6; in other words, the ratio of surface to volume

has been halved by growth. Three successive bipartitions of the

larger cube will divide it into eight separate 1-centimetre cubes,

each now possessing the original ratio of surface to volume.

[34] The nucleus is regarded by some as equivalent to a central nervous

organ for the cell; by others, such as G. Mann and Verworn, as the

chief chemical centre of the cell, and notably the seat of the

secretion of the zymases or ferments that play so important a part in

its life-work; for it is found that a Protist deprived of its nucleus

can execute its wonted movements, but can neither digest nor grow.

This conclusion may appear to be rather sweeping and premature, but

we have seen that the changes of surface tension are the direct

antecedents of the motions of the cytoplasm, we know that such

changes are induced by chemical changes; and thus the nucleus—if it

be the central laboratory to which such changes are ultimately

due—would really in a certain sense be a directive centre.

[35] The term "resting" is very ill-chosen, for even superficial

observation shows that the relative position and characters of the

internal structures of such a nucleus are constantly changing with

the vital activities and functions of the cell.

[36] For a detailed study of the nucleus in Protista, see Calkins in

_Arch. Protistenk._ vol. ii. 1903.

[37] The "centriole" is a minute granule sometimes recognisable in the

centre of the centrosphere, and undergoing fission in advance. But

centrosomes are often found without a distinction into centrosphere

and centriole, and there is much confusion in the use of the terms.

[38] The origin of the centrosomes is a problem not yet certainly solved,

if indeed it be susceptible of any universal solution. They are

certainly absent in many plants; and, on the other hand, structures

which correspond to them often appear in mitotic divisions of

Protista. In some cases the centrosomes are undoubtedly of nuclear

origin, and pass out through the nuclear wall into the cytoplasm.

[39] Though the forces at work in the dividing cell are similar in their

effects to such physical forces as magnetism, static electricity, and

even capillarity, and models utilising such physical forces have been

devised to represent the strain-figures of the cell, the cell forces

are distinct from any known physical force. For discussions of the

nature of the forces at work, with bibliographies, see Angel

Gallardo, _Interpretatión Dinámica de la División Celular_, 1902;

Rhumbler, in _Arch. Entw._ xvi. 1903, p. 476; Hartog, _C.R._

cxxxviii. 1904, p. 1525, and "On the Dual Force of the

Dividing-cell," pt. i. _Proc. Roy. Soc._ 1905 B, lxxvi. p. 548.

[40] See Th. Boveri, _Ergebnisse ueb. d. Konstitution d. chromatischen

Substanz des Zellkerns_ (1903), for the most recent defence of this

view. He lays, however (p. 2), far more stress on the individuality

of the segments themselves than on the actual chromatin material they

contain.

[41] The fact that it is by mitotic division that the undifferentiated

germ-cells produce the "differentiated" tissue-cells of the body of

the highest animals, is again irreconcilable with such theories,

whose chief advocates have been A. Weismann and his disciples.

[42] Temporary plastogamy is a process found in some Foraminifera, where

two organisms unite by their cytoplasms so that there can be complete

blending of these, while the nuclei remain distinct: they ultimately

separate again. In the conjugation of the Infusoria, the union of the

cytoplasms is a temporary plastogamy (see p. 148 f.).

[43] See Figs. 9, 29, 31, 34, etc., pp. 54, 89, 95, 101.

[44] One obvious effect of brood-formation is to augment rapidly the ratio

of superficial area to bulk: after only three divisions (p. 23, note)

the ratio is doubled; if the divisions be nine in succession so as to

produce a brood of 512, the ratio is increased eightfold, on the

supposition that the figure is preserved. However, the

brood-mother-cell is usually spherical, while zoospores are mostly

elongated, thus giving an additional increase to the surface, which

we may correlate with that increased activity; so that they

disseminate the species, spreading far and wide, and justifying the

name of "spore" in its primitive sense (from the Greek σπείρω—I

scatter [seed]).

[45] This condition may be protracted in the segmentation of the egg of

certain Higher Animals, such as _Peripatus_ (Vol. V. p. 20). It is

clearly only a secondary and derived condition.

[46] The usual antecedent of change in the condition of the egg is

"fertilisation"—its conjugation with the sperm; but this is not

invariable; and a transitory sojourn of certain marine eggs in a

liquid containing other substances than sea-water may induce the egg

on its return to its native habitat to segment and develop. This has

been mistermed "Chemical fertilisation," discovered within the last

six years by Jacques Loeb, and already the subject of an enormous

literature.

[47] See Hartog in _Rep. Brit. Ass._ 1896, p. 933, 1900, p. 786.

[48] Commonly called "fertilisation," or "sexual union," inadequate and

misleading terms.

[49] For details see Hartog, "Some Problems of Reproduction," _Quart.

Journ. Micr. Sci._ xxxiii. p. 1, xlvii. p. 583; and _Ann. Biol._ vol.

iv. (1895) 1897; E. B. Wilson, Yves Delage, and Henneguy (references

on p. 3, note); and for a singularly clear and full treatment of the

processes in Protozoa, Arnold Lang, _Lehrb. d. Vergl. Anat._ 2nd ed.

Lief. 2, "Protozoa," 1900.

[50] This phenomenon, which we have termed "exogamy," is common in

Protophyta; it has been clearly demonstrated by Schaudinn in

Foraminifera and the Lobose Rhizopod _Trichosphaerium_ (p. 53 f. Fig.

9), and by Pringsheim in the Volvocine _Pandorina_ (p. 128 f. Fig.

45). It is quite independent of the differentiation of _binary_ sex.

[51] Other modes of syngamy, such as karyogamy and plastogamy, we shall

discuss below, pp. 69, 148; see also p. 30.

[52] See Gruber in _Biol. Centralb._ iv. p. 710, v. p. 137 (1884-6), in

_Ber. Ges. Freiburg_, i. ii. 1886-7; Verworn (reference on p. 16); F.

R. Lillie in _Journ. Morph._ xii. 1896, p. 239; Nussbaum in _Arch.

mikr. Anat._ xxvi. 1886, p. 485; Balbiani in _Recueil Zool. Suisse_,

v. 1888, in _Zool. Anz._ 1891, pp. 312, 323, in _Arch. Microgr._ iv.

v. 1892-3. For Higher Organisms especially see T. H. Morgan,

_Regeneration_, 1901.

[53] Whence the antiseptic powers of such aromatic alcohols as phenol and

thymol, and acids as salicylic acid, etc., and their salts and

esters.

[54] The portion of the spectrum that is operative in "holophytic"

nutrition is the red or less refrangible half, and notably those rays

in the true red, which are absorbed by the green pigment chlorophyll,

and so give a dark band in the red of its absorption spectrum. The

more refrangible half of the spectrum, so active on silver salts,

that it is usually said to consist of "chemical rays," is not only

inoperative, but has a destructive action on the pigments themselves,

and even on the protoplasm. Chlorophyll is present in all cases even

when more or less modified or masked by the accompaniment of other

pigments.

[55] Similarly, threads unite the cells of the colonial plant—Flagellate

_Volvox_, passing through the thick gelatinous cell-wall (pp.

126-127, Fig. 44).

[56] Pigments soluble in the ordinary solvents of fats, such as ether,

benzol, chloroform, etc.

[57] We have ourselves had hard work to persuade intelligent men of fair

general education, even belonging to a learned profession, that this

is not the case.

[58] Dr. H. Charlton Bastian has recently maintained a contrary thesis

(_The Nature and Origin of Living Matter_, 1905), but has adduced no

evidence likely to convince any one familiar with the continuous

life-study of the lower organisms.

[59] The terms "organoid," "organella," have been introduced to designate

a definite portion of a Protist specialised for a definite function;

the term "organ" being reserved for a similarly specialised group of

cells or tissues in a Metazoon or Metaphyte. We do not consider that

this distinction warrants the introduction of new words into the

terminology of general Zoology, however convenient these may be in an

essay on the particular question involved.

[60] This has been especially the case with the Flagellata, the

Proteomyxa, and the Mycetozoa.

[61] Lang distinguishes "lobopodia," "filopodia," and "pseudopodia"

according to their form,—blunt, thread-like, or anastomosing. In some

cases the protoplasm shows a gliding motion as a whole without any

distinct pseudopodium, as in _Amoeba limax_ (Fig. 1, p. 5), and a

pseudopodium may pass into a thin, active flagellum, which is,

however, glutinous and serves for the capture of prey: such often

occurs in the Lobosa _Podostoma_ and _Arcuothrix_, which are possibly

two names for one species or at least one genus; and in many cases a

slender pseudopodium may be waved freely.

[62] See Schewiakoff, "Ueb. d. Geograph. Verbreitung d.

Süsswasserprotozoen," in _Mém. Acad. St. Pétersb._ ser. 7, xli. 1893,

No. 8. His views apply to most minute aquatic organisms—Animal,

Vegetable, or Protistic.

[63] See E. R. Lankester, art. "Protozoa" in _Encycl. Brit._ 9th ed.

(1885), reprinted with additions in "Zoological Articles." We cannot

accept his primary division into Corticata and Gymnomyxa, which would

split up the Flagellata and mark off the Gregarines from the other

Sporozoa.

[64] On this ground I have referred _Paramoeba_, Greeff, to the

Cryptomonadineae.

[65] Differences (1) from _Foraminifera_; (2) from _Heliozoa_; (3) from

_Proteomyxa_ and _Sporozoa_; (4) from _Myxomycetes_; (5) from many

_Foraminifera_.

[66] I have not followed the usual classification into Gymnamoebae and

Thecamoebae, according to the absence or presence of a test

(perforated by one or more openings) in the active state, as such a

test occurs in isolated genera of Flagellata and Infusoria, and does

not appear to have any great systematic importance.

[67] The significance of chromidia in Sarcodina (first noted by Schaudinn

in Foraminifera) was fully recognised and generalised by R. Hertwig

in _Arch. Protist._ i. 1902, p. 1.

[68] Stolč in _Z. wiss. Zool._ lxviii. 1900, p. 625. Lilian Veley,

however, gives reasons for regarding them as of proteid composition,

_J. Linn. Soc._ (_Zool._) xxix. 1905, p. 374 f. They disappear when

the _Pelomyxa_ is starved or supplied with only proteid food.

[69] This genus contains two sausage-shaped, blueish-green plastids,

possibly symbiotic Cyanophyceous Algae.

[70] See Lauterborn in _Z. wiss. Zool._ lix. 1895, pp. 167, 537.

[71] C. Scheel has seen _Amoeba proteus_ produce a brood of 500-600 young

amoebulae, which he reared to full size (in _Festschr. f. Kupffer_,

1899).

[72] _Arb. Kais. Gesundheitsamte Berlin_, xix. 1903.

[73] _Faune Rhizopodique du Bassin du Léman_, 1902. See also Cash, _The

British Freshwater Rhizopoda and Heliozoa_, vol. i., Ray Society,

1905.

[74] Chapman, _The Foraminifera_, London, 1902; Lister, "Foraminifera" in

Lankester's _Treatise on Zoology_, pt. i. fasc. 2, 1903.

[75] _Challenger Reports_ (_Zool_.), vol. ix. 1884.

[76] In Lankester's _Treat. Zool._ pt. i. fasc. 1. For other

classifications see Eimer and Fickert in _Z. wiss. Zool._ lxv. 1899;

Rhumbler in Lang's _Protozoa_, 1901; and for a full synopsis of

genera and species, "Systematische Zusammenstellung der recenten

Reticulosae" (pt. i. only), in _Arch. Prot._ iii. 1903-4, p. 181.

[77] The type of Dujardin's genus _Gromia_ is _G. oviformis_ = _Hyalopus

dujardinii_, M. Sch., which is one of the Filosa.

[78] This convenient name is due to my friend Dr. A. Kemna of Antwerp.

[79] The name Foraminifera was used to express the fact that the chambers

communicated by pores, not by a tubular siphon as in Nautiloidea and

Ammonoidea (Vol. III. pp. 393, 396).

[80] Which probably accounts for the earlier failure of Lister and of

Schaudinn himself to note their conjugation.

[81] Rhumbler, "Die Doppelschalen v. _Orbitolites_ u. and. Foraminiferen,"

in _Arch. Protist._ i. 1902, p. 193.

[82] The alleged Archaean genus _Eozoon_, founded by Carpenter and Dawson

on structures found in the Lower Laurentian serpentines

(ophicalcites), and referred to the close proximity of Nummulites,

has been claimed as of purely mineral structure by the petrologists;

and recent biologists have admitted this claim.

[83] Possibly composed of the same proteid, "acanthin," that forms

spicules of greater permanence in the Acantharia among the Radiolaria

(p. 75 f. Figs. 24, 25, A).

[84] Such divisions into functional and abortive sister nuclei are termed

"reducing divisions," and are not infrequent in the formation of

pairing-cells, especially oospheres of Metazoa, where the process is

termed the maturation of the ovum.

[85] Besides these genera enumerated by Schaudinn, we include _Dimorpha_

Gruber (Fig. 37 5, p. 112), _Mastigophrys_ Frenzel, _Ciliophrys_

Cienk., and _Actinomonas_ usually referred to Flagellates.

[86] K. Brandt, in _Arch. Prot._ i. 1902, p. 59, regards the presence of

spicules as not even of generic moment, and subdivides the Collodaria

into two families—_Collida_ (solitary), and _Sphaerozoea_, colonial,

_i.e._ with numerous central capsules.

[87] Dreyer adds an additional order—Sphaeropylida, distinguished by a

basal (or a basal and an apical) pylome.

[88] Verworn has shown that _Thalassicolla nucleata_ can, when the

exoplasm is removed from the central capsule, regenerate it

completely. First a delicate exoplasm gives off numerous fine

radiating pseudopodia, and the jelly is re-formed at their bases, and

carries them farther out from the central capsule. See _General

Physiology_ (Engl. ed. 1899), p. 379.

[89] The pigment is singularly resistant and insoluble, and shows no

proteid reaction. Borgert states that it appears to be formed in the

oral part of the endoplasm, and to pass through the astropyle into

the ectoplasm, where it accumulates. It is probably a product of

excretion, and may serve, by its retention, indirectly to augment the

surface. See Borgert, "Ueb. die Fortpflanzung der tripyleen

Radiolarien" in _Zool. Jahrb. Anat._ xiv. 1900, p. 203.

[90] Dreyer has shown that in many cases it may be explained by

geometrical considerations. V. Häcker has written a most valuable

account of the Biological relations of the skeleton of Radiolaria in

_Jen. Zeitschr._ xxxix. 1904, p. 297.

[91] _Zool. Jahrb. Anat._ xiv. 1900, p. 203.

[92] Porta has described reproduction by spores and by budding in

Acantharia, _Rend. R. Ist. Lomb._ xxxiv. 1901 (ex _Journ. R. Micr.

Soc._ 1903, p. 45). In _Thalassophysa_ and its allies zoospore

reproduction appears to be replaced by a process in which the central

capsule loses its membrane, elongates, becomes multinuclear, and

ultimately breaks up into the nucleate portions, each annexing an

envelope of ectoplasm to become a new individual (see _Arch. Prot._

vol. i. 1902).

[93] Brandt, "Die Koloniebildenden Radiolarien," in _Fauna u. Flora des

Golfes v. Neapel_, xiii. 1885, gives a full account of the

Zooxanthellae and Diatoms, and notes the parasitism of _Hyperia_.

[94] See Köppen in _Zool. Anz._ xvii. 1894, p. 417. For _Sticholonche_,

see R. Hertwig in _Jena. Zeitsch._ xi. 1877, p. 324; and Korotneff in

_Zeitsch. wiss. Zool._ li. 1891, p. 613. Borgert's paper on

Dictyochidae is in the same volume, p. 629.

[95] Most of Haeckel's Monera, described as non-nucleate, belong here.

Several have been proved to be nucleate, and to be rightly placed

here; and all require renewed study.

[96] Even the Acystosporidiae have sickle-germs (blasts) in the insect

host.

[97] See Zopf, _Beitr. Nied. Org._ ii. 1892, p. 36, iv. 1894, p. 60, for

the doubtful genus _Chlamydomyxa_; Hieronymus, abstracted by

Jenkinson, in _Quart. J. Micr. Sci._ xiii. 1899; Penard, _Arch.

Protist._ iv. 1904, p. 296.

[98] The name "aethalium" is now always used in this sense.

[99] The group was monographed by Schröter in Engler and Prantl's

_Pflanzenfamilien_, I. Teil, Abt. 1, 1897. See also A. Lister's

Monograph of the Mycetozoa, 1894; Massee, Monog. of the Myxogastres,

1893; Sir Edward and Agnes Fry, _The Mycetozoa_, 1899; and Massee

MacBride, _The North American Slime Moulds_, 1899.

[100] Several monographs of the group have been published recently dealing

with the group from a systematic point of view, including their

relation to their hosts. Wasielewski, "Sporozoenkunde" (1896); Labbé,

"Sporozoa" (in _Tierreich_, 1899). Doflein's "Protozoen als Parasiten

und Krankheitserreger" (1901) contains most valuable information of

the diseases produced by these and other Protozoic hosts. Minchin's

Monograph in Lankester's _Treatise on Zoology_, pt. i. fasc. 2

(1903), is a full account of the class, and admirable in every way.

[101] For its reactions see Bütschli, _Arch. Protist._ vii. 1906, p. 197.

[102] The cuticle in the allied genus _Lankesteria_, which is the form we

figure on p. 95, is perforated by a terminal pore, through which the

clear plasma of the sarcocyte may protrude as a pseudopodium.

[103] This account is taken from Cuénot (in _Arch. de Biol._ 1900, p. 49),

which confirms Siedlecki's account of the process in the allied genus

_Lankesteria_ in _Bull. Acad. Cracow_, 1899. Wolters's previous

description, assimilating the processes to those of _Actinophrys_, is

by these authors explained as the result of imperfect preservation of

his material.

[104] See p. 120.

[105] See Caullery and Mesnil, "Rech. sur les Actinomyxidies," _Arch. Bot._

vi. 1905, p. 272 f.

[106] Léger, _Arch. Zool. Exp._ sér. 3, x. and sér. 4, v. (1902-3); for a

full discussion of the relations of association and conjugation in

Gregarines, see Woodcock in _Quart. Journ. Micr. Sci._ l. 1906, p. 61

f.

[107] A _Lithobius_ is figured in Vol. V. p. 45.

[108] The schizont forms of some species, before the invariable alternation

of schizogony and sporogony had been made out clearly, were regarded

as "monogenic" genera, under the names of _Eimeria_, A. Schn., and

_Pfeifferella_, Labbé; while those in which the formation of spores

containing sickles had been clearly seen were termed "digenic."

Labbé's monograph, "Die Sporozoen," in the _Tierreich_, is

unfortunately written from this point of view, which had already

become doubtful, and is now demonstrated to be erroneous, chiefly by

the labours of Schaudinn and Siedlecki.

[109] A species has been described, however, in the blood of the Indian

Gerbille (_Gerbillus indicus_), completing the sexual process in the

Louse of its host. A figure of _G. aegyptius_ will be found in Vol.

X. (1902) p. 475.

[110] There is no difference between a mosquito (little fly) and a gnat,

both names are applied indiscriminately to thin-bodied Diptera of the

group Nemocera which attack man; only the females bite (see Vol. VI.

pp. 466-468).

[111] Regarded by Schaudinn as a state of the Flagellate _Trypanosoma_ (p.

119 f.).

[112] In _Quart. Journ. Micr. Sci._ xliv. 1901, p. 429.

[113] It would seem that resting-cells, _i.e._ the crescents and

corresponding spheres, of _Laverania_ and _Haemamoeba_ may linger

during months of apparent health in the spleen and red marrow of the

bones; and that these by parthenogenesis produce sporozoites and

determine relapses when, owing to a lowering of the general health,

conditions favourable to new sporulation occur.

[114] Léger and Duboscq have found that _Sarcocystis tenella_, a parasite

common in the muscles of the sheep (and rarely found in man), has a

conjugation and sexual process recalling that of _Stylorhynchus_,

save that the sperms are much smaller than the ova (_C.R._ 1902, i.

p. 1148).

[115] The alleged micronucleus of certain forms appears to be merely a

"blepharoplast" (see p. 19); even when of nuclear origin, as in

_Trypanosoma_, it has no function in reproduction like the

micronucleus of Infusoria (see pp. 115, 120 f.).

[116] _Dimorpha_ is now referred to Heliozoa (p. 70).

[117] _I.e._ resembling the thread-like water Algae.

[118] Trichocysts (see p. 142) occur in some Chloromonadaceae; and the

Dinoflagellate _Polykrikos_ possesses true nematocysts (see p. 131).

[119] For a full monograph of this family see H. Lohmann, in _Arch. f.

Protistenkunde_, vol. i. 1902, p. 89.

[120] Delage has well explained the action of the single anterior flagellum

which waves in a continuous spiral like a loaded string whirled round

one's head; it thus induces a movement of the water, beyond its

actual range, backwards and outwards, maintained by a constant influx

from behind, which carries the cell onward at the same time that it

necessarily rotates round its axis. If there is a pair of

symmetrically placed flagella they co-operate like the arms of a

swimmer; when the second flagellum is unilateral the motion is most

erratic, as seen in the Bodonidae (and the zoospores of many

Chytridieae, which have most of the characters of the Flagellates,

though habitually removed to the Fungi).

[121] The colouring matter is chlorophyll or some allied colouring matter.

In the yellow and brown forms the additional pigment is termed

loosely "diatomin," but its identity with that of Diatoms is in no

case proved.

[122] Notably in the Craspedomonadidae, where transverse division also

occurs. See Raoul Francé, _Die Craspedomonadineen_ (Buda-Pesth,

1897).

[123] And also in the "Monads," described by Dallinger and Drysdale, see

above.

[124] In _Cercomonas dujardinii_, _Polytoma uvella_, and _Tetramitus

rostratus_ the gametes resemble the ordinary forms and are isogamous.

In _Monas dallingeri_ and _Bodo caudatus_ conjugation takes place

between one of the ordinary form and size and another similar but

smaller. In _Dallingeria drysdali_ the one has the ordinary size and

form, the other is equal in size, but has only one flagellum, not

three; in _Bodo saltans_ they are unequal, the larger gamete arising

in the ordinary way by longitudinal fission, the smaller by

transverse division. Doubt has been thrown on the validity of our

authors' results by subsequent observers abroad; but I can find no

evidence that these have even attempted to repeat the English

observations under the same severely critical conditions, and

therefore consider the attacks so far unjustified. Schaudinn has

observed conjugation between _Trichomonas_ individuals which have

lost their flagella and become amoeboid; also in _Lamblia

intestinalis_ and in _Trypanosoma_ (_Halteridium_?) _noctuae_ (Fig.

39) "Reduction-divisions" (see p. 75, note 1) of the nuclei take

place before fusion, and the nuclear phenomena are described as

"complicated" (_Arb. Kais. Gesundheitsamte_, xx. 1904, p. 387).

_Paramoeba eilhardii_ in its adult state is colourless, amoeboid,

multiciliate. It forms a brood cyst, from which are liberated

flagellate zoospores, with a chromatophore, which reproduce by

longitudinal fission in this state. They may also conjugate.

[125] In _P.R.S._ xxvii. 1878, p. 332.

[126] In _Z. wiss. Zool._ lv. 1893, p. 353.

[127] 1. Teil, Abt. 1. a, 1900.

[128] In the _Chlorophyceae_, 1. Teil, Abt. 2, 1897.

[129] 1. Teil, Abt. 1. b, 1896.

[130] Besides the above, Dangeard, in various papers in his periodical _Le

Botaniste_, has treated of most of the groups, and Raoul Francé has

monographed the _Polytomeae_ in the _Jahrb. wiss. Bot._ xxvi. 1894,

p. 295, and Dill the genus _Chlamydomonas_, etc., its closest allies,

in _op. cit._ xxviii. 1895, p. 323.

[131] For a detailed abstract of our knowledge of _Trypanosoma_ and its

allies up to Feb. 1, 1906, see Woodcock, "The Haemoflagellates," in

_Quart. Journ. Micr. Sci._ 1. 1906, p. 151.

[132] Doubts still subsist as to the interpretation of Schaudinn's

observations.

[133] _Quart. Journ. Micr. Sci._ xlvi. 1902.

[134] A Zambezian Tick infects man with a _Treponema_, producing

relapsing-fever; another species is found in the tropical disease

"framboesia" ("yaws" or "parangi").

[135] Stated by Geza Entz and Raoul Francé to be due to the spiral twisting

of a plasmic membrane, and to be like a cone formed by twisting

paper, with the free edges overlapping.

[136] Discovered by Leidy. For the most recent description of this group

see Grassi and Sandias in _Quart. Journ. Micr. Sci._ xxxix. (figures)

and xl. p. 1 (text), 1897.

[137] Bezzenberger has given an analytical table of the eleven known

species of the genus _Opalina_ in _Arch. Protist._ iii. 1903, p. 138.

[138] Such movements, permissible by the perfectly flexible but firm

pellicle, are termed "metabolic" or "euglenoid" in contradistinction

to "amoeboid." They also occur in many Sporozoa.

[139] Within which is often harboured the Rotifer, _Proales parasita_, Vol.

II. p. 227.

[140] In the Adinidae there is no groove; the two lashes arise close

together, and the one is coiled round the base of the other.

[141] In _Unt. Inst. Tübingen_, i. 1883, p. 233.

[142] Conjugation of adults has been observed by Zederbauer (_Ber. Deutsch.

Ges._ xxii. 1904). A short connecting tube is formed by the meeting

of outgrowths from either mate; their protoplasmic contents meet and

fuse herein to form a spherical resting-spore, as in the Conjugate

Algae.

[143] According to Bergh, _Polykrikos_ has as many nuclei as grooves, each

accompanied by one or more "micronuclei." Possibly these latter

bodies are merely blepharoplasts, in connexion with the transverse

flagella.

[144] Engler and Prantl's _Pflanzenfamilien_, 1. Teil, Abt. 1, 1896.

[145] The luminous genus, _Pyrocystis_ (Fig. 47), regarded as a

Cystoflagellate by Wyville Thomson, has a cellulose wall, no mouth,

and in the zoospore state has the two flagella in longitudinal and

transverse grooves of the Dinoflagellata.

[146] This process has the character of telolecithal segmentation in a

Metazoan egg.

[147] See Doflein, in _Zool. Jahrb. Anat._ xiv. 1900, p. 1.

[148] London, 1753, 402-403.

[149] On this account Hickson has termed the group "Heterokaryota" in

Lankester's _Treat. Zool._ i. fasc. 1, 1903.

[150] See Baker, _Employment for the Microscope_, ed. 2, 1758.

[151] Saville Kent's valuable _Manual of the Infusoria_ (1880-1882), which

gives figures of every genus and descriptions of every species known

at that date, includes the Flagellates in its scope.

[152] Orders 1 and 2 constitute together the _Holotricha_ of Stein;

Bütschli regards 3 to 6 as sections of _Spirotrocha_.

[153] Dextrorse in all but _Lichnophora_ and _Spirochona_.

[154] Each membranella is a transversely elongated oval in reality, and

below it is a double row of basal granules, corresponding to the

individual cilia that constitute it. Similarly, the undulating

membranes have a single row of basal granules.

[155] Tail-like appendages are found in _Scaphiodon_ and in _Dysteria_ and

its allies (Gymnostomaceae), _Urocentrum_ (Aspirotrichaceae),

_Discomorpha_ and _Caenomorpha_ (Heterotrichaceae). In the first two

and last two cases they are prolongations of the body; in the third

an aggregate of cilia. One or more long caudal setiform cilia are

present in the genera _Lembadion_, _Pleuronema_, _Cyclidium_,

_Lembus_, _Cinetochilum_, _Ancistrum_, and _Uronema_; all these are

addicted to making springing darts. Tufts of cilia of exceptional

character often serve for temporary attachment. The stalk (or at

least its external tube) of the Peritrichaceae appears to be the

chitinous excretion of a zone of such cilia. Fauré-Fremiet terms such

a zone or annular brush a "scopula" ("Struct. de l'app. fixateur chez

les Vorticellides," _Arch. Protist._ vi. 1905, p. 207). For a

discussion of the finer structure of the cilia in Ciliata, and the

mechanism of their action, see Schuberg, _Arch. Protist._ vi. 1905,

p. 61.

[156] See Mitrophanow "Sur les Trichocystes ... du _Paramoecium_," _Arch.

Protist._ v. 1904, p. 78.

[157] The "neurophane" fibrils of Neresheimer, _Arch. Protist._ ii. 1903,

p. 305 f.

[158] Sometimes the number of afferent canals is limited to five

(_Paramecium_), or even one. There may be one or more contractile

vacuoles, and in the latter case the different ones have an

independent rhythm.

[159] It is from such conclusive cases that the universal character of a

discharge to the surface has been inferred in the rest of Protista

possessing this organ.

[160] _Gruber_ (_Ber. Ges. Freib._ 1888) has shown that in several marine

Ciliata the meganucleus is represented by an enormous number of

minute granules disseminated through the endosarc, which, on the

approach of fission, unite into a single meganucleus. As an adjacent

micronucleus makes its appearance at this stage, he infers that the

micronucleus must be also resolved in the intermediate life of the

cell into granules too small for recognition under the highest

magnification attainable, and that they must then coalesce.

[161] In the peculiar Peritrichan _Spirochona_ the division of the

meganucleus is a much more complex process than usual, and recalls

that of the undifferentiated nuclei of many Rhizopods (see Rompel in

_Z. wiss. Zool._ lviii. 1894, p. 618). _Opalina_ has neither mouth

nor anus, nor contractile vacuole, but a large number of similar

nuclei, that divide by a true mitotic process, like micronuclei. We

have referred it (pp. 114, 123) to the Flagellates, next to the

Trichonymphidae.

[162] Save the Opalinopsidae, which are usually termed "Opalinidae"; but

which cannot retain the latter name on the removal of the genus

_Opalina_ to the Flagellates.

[163] _Phil. Trans._ clxxxv. 1895, pp. 355 f.

[164] _Arch. Zool. Exp._ (2) vi. vii. 1888-1889.

[165] Calkins has recently found that the vitality within a cycle is

rhythmical, with alternations of more and of less frequent fissions,

under the same set of conditions; and that minute doses of beef-tea

or various mineral salts will not only keep up the higher rate, but

even stave off senescence. Minute doses of alcohol will keep up the

higher rate, but not avert senescence. He considers that Maupas'

generalisations are in most respects too sweeping (_Arch. Entw._ xv.

1902, p. 139). But Dr. James Y. Simpson informs me that the

possibility of stimulative regeneration has been found to be limited.

See also Calkins and Lieb, _Arch. Prot._ i. 1902, p. 355.

[166] As inferred by Hickson from the prolongation of the union.

[167] When there are at the outset two or more micronuclei all undergo the

first two fissions, but only one undergoes the third.

[168] _Zeitschr. wiss. Zool._ xxxiii. 1880, p. 439.

[169] Bezzenberger has given a key to the species of these two genera in

_Arch. Prot._ iii. 1903, pp. 149, 157.

[170] We note that _Lacrymaria_ is prolonged in front into a long, slender

flexible "neck," with the mouth terminal. This swan-like conformation

is "mimicked" by _Dileptus_ and _Lionotus_, where the neck, like the

prostomium of worms, is a mere extension of the front of the body

above and beyond the mouth; all three swim with peculiar grace.

_Trachelius_ (Fig. 56) has a distinct cup-shaped sucker behind the

mouth, and is remarkable, like _Loxodes_, for the branching

disposition of its endosarc.

[171] The pigment of this species has been examined and described by

Lankester under the name of "blue stentorin" (_Quart. Journ. Micr.

Sci._ xii. 1873).

[172] For a full account of _Caenomorpha_, _Metopus_, and allied forms, see

Levander, _Beitr. z. Kenntn. einiger Ciliaten_, Dissert. Helsingfors,

1894.

[173] _Torquatella typica_, described by Lankester as possessing a

continuous undulating membrane for its peristomial wreath, is

identified by Bütschli as a _Strombidium_, possessing exceptionally

large membranellae.

[174] Outside the principal wreath is another of fine cilia ("paroral"),

standing out at an angle.

[175] Covered with a rather lax structureless membrane (sarcolemma), which

is spirally wrinkled when the muscle contracts. I am unable to verify

Geza Entz's observations, adopted by Calkins and Delage.

[176] Of the composition of cellulose (Halliburton, in _Quart. Journ. Micr.

Sci._ xxv. 1885, p. 445).

[177] As does the Hypotrichan _Kerona polyporum_.

[178] Permanently ciliate in _Hypocoma_ and _Suctorella_.

[179] In this case the débris of the live prey torn up by the _Cyclops_ on

which they live.

[180] The spiral ridge figured by Hertwig (Fig. 61, 1. _c_) is probably an

incorrect representation of this structure, exceedingly minute in all

genera but _Choanophrya_.

[181] In _Choanophrya_ I have failed to find any pore, and believe the

bud-formation to be strictly endogenous.

[182] See _Quart. Journ. Micr. Sc._ xlv. 1902, p. 325.

[183] In _Journ. Coll. Sc. Japan_, x. 1896.

[184] _Étude monographique sur le groupe des Tentaculifères, Ann. Soc.

Belge Micr._ xxiv.-xxvi. 1901.

[185] To Professor W. J. Sollas, Sc.D., F.R.S., who undertook to write the

chapters on Porifera when the work was first planned, the Author and

the Editors are indebted for his kind assistance in reading and

criticising this article.

[186] _Rarities belonging to the Royal Society preserved at Gresham

College_, 1686.

[187] _Gerarde's Herbal, enlarged and revised by Thomas Johnson_, 1636, p.

1587.

[188] _Phil. Trans._ lv. p. 280.

[189] _Histoire Phys. de la Mer_, 1725.

[190] _Mem. Boston Soc._ i. 1867, p. 305.

[191] _Zeitschr. wiss. Zool._ xxxi. 1878, p. 262.

[192] _Ann. Mag. Nat. Hist._ (5) xiii. 1884, p. 381.

[193] _Quart. Journ. Micr. Sci._ xxiv. 1884, p. 612.

[194] The name was coined by Dr. Fleming from χάλιξ "silex" and χόνδρος

"cartilage," and as these roots could only give _Chalic-chondria_ it

is not surprising that those who have not referred to Dr. Fleming's

statements give the derivation as ἅλς "sea" and χόνδρος.

[195] _Monograph of British Sponges_, vol. iii. pl. xxxix.-xl. For revision

of nomenclature in this Monograph, see Hanitsch, _Tr. Liverp. Biol.

Soc._ viii. 1894, p. 173.

[196] _Journ. Physiol._ ix. 1888, p. 1.

[197] Sollas, _Ann. Mag. Nat. Hist._ (4) xx. 1877, p. 285; Bütschli,

_Zeitschr. f. wiss. Zool._ xix. 1901, p. 236.

[198] Minchin, "Sponges" in _Treatise on Zoology_, edited by E. Ray

Lankester, p. 87. See also Bidder, _Proc. Roy. Soc._ li. 1892, p.

474.

[199] _Zool. Jahrb. Anat._ vii. 1894.

[200] _Materials for the Study of Variation_, 1894, p. 30.

[201] _Arch. de Zool. Exp._ (2) x. 1892, pp. 345-498. On the general

subject of adhesion of species, see Bowerbank, _Brit. Ass. Rep._

1857, p. 11, who quotes Grant as the first to observe the phenomenon.

[202] _Quart. Journ. Micr. Sci._ xxii. 1882, p. 229.

[203] But see Gamble and Keeble, _Quart. Journ. Micr. Sci._ xlvii. 1904, p.

363, who show that various green animals really owe their colour to

"algae," though the infection with the "alga" is difficult to detect

because it takes place by means of a colourless cell. See also

_Zoochlorella_, on p. 126.

[204] Sollas, _Tr. Dublin Soc._ (2) iii. 1884, p. 87.

[205] _Arch. Naturg._ lix. 1893, p. 246.

[206] Weltner, _Blatt. Aquar. Fr._ vii. 1896, p. 277, and

"Spongillidenstudien," _Arch. Naturg._ ii. 1893, p. 271.

[207] Evans, _Quart. Journ. Micr. Sci._ xliv. 1900, p. 72.

[208] _Ann. Mag. Nat. Hist._ (2), x. 1882, p. 365.

[209] _P. Ac. Philad._ 1887, pp. 158-278.

[210] Evans, _Quart. Journ. Micr. Sci._ xlii. 1899, p. 363.

[211] Francé, _Organismus der Craspedomonaden_, Budapest, 1897, p. 217.

[212] Sollas, _Encyclopædia Britannica_, art. "Sponges," 1887.

[213] Sollas, _Ann. Mag. Nat. Hist._ (5) iii. 1879, p. 23; _Challenger

Report_, vol. xxv. pt. lxiii. 1888, p. lii.

[214] Minchin, Lankester's _Treatise on Zoology_, pt. ii. 1900.

[215] Minchin, _loc. cit._ p. 110.

[216] Bidder, _Quart. Journ. Micr. Sci._ xxxii. 1891, p. 631, and Minchin,

_Quart. Journ. Micr. Sci._ xxxiii. 1892, p. 266.

[217] Minchin, Lankester's _Treatise on Zoology_, p. 30.

[218] Vosmaer and Pekelharing, _Verh. Ak. Amsterdam_, (2) vi. 3, 1898, p.

1.

[219] Dendy, _Quart. Journ. Micr. Sci._ xxxv. 1894, p. 230.

[220] Maas, _Zeitschr. wiss. Zool._ lxvii. 1899-1900, p. 215.

[221] "Die Kalkschwämme," 1871.

[222] Dendy. _loc. cit._ p. 159.

[223] _Quart. Journ. Micr. Sci._ xxxvi. 1894, p. 127.

[224] Doederlein, _Zool. Jahrb. Abth. Anat._ x. 1896, p. 15, pl. ii. and

iii.

[225] Hinde, _Quart. Journ. Geol. Soc._ lvi. 1900, p. 50.

[226] Hinde, _Tr. R. Micr. Soc._ 1904, p. 3.

[227] Počta, _Bull. Acad. Bohème_, 1903.

[228] J. J. Lister in Willey's _Zoological Results_, pt. iv. 1900, p. 459.

[229] _Mém. Soc. Zool. France_, 1896, p. 119.

[230] _Arch. Zool. Exp._ (3) iii. 1895, p. 561, pl. xxiii.

[231] F. E. Schulze, _Challenger Monograph_, xxi.

[232] Chun, "Aus den Tiefen des Weltmeeres," 1900, p. 481.

[233] Shipley, "Fauna of the Antarctic Regions." See also p. 216.

[234] _J. Coll. Japan_, xv. 1901, pp. 128, 147, 190.

[235] _Fauna Arctica_ (Roemer and Schaudinn), i. 1900, p. 84; and _Sitzb.

Akad. Berlin_, 1899, p. 98.

[236] Sollas, _Quart. Journ. Geol. Soc._ 1880, p. 362.

[237] _Quart. Journ. Geol. Soc._ xl. 1884, p. 795.

[238] "Monograph British Fossil Sponges," _Palaeont. Soc._ xl. and xli.

1887 and 1888.

[239] Sollas, _Challenger Monograph_, xxv. 1888.

[240] _Marine Investigations in South Africa_, i. 1902, p. 224.

[241] Cf. Sollas, _Encyclopædia Britannica_, 1887, art. "Sponges," and

Schrammen, _Mitth. Mus. Hildesheim_, 14, 1901.

[242] Sollas, _Quart. Journ. Geol. Soc._ xxxiii. 1877, p. 790.

[243] Ridley and Dendy, _Challenger Monograph_, lix. 1887.

[244] _Ibid._ p. 262; cf. also p. 197.

[245] _Quart. J. Micr. Sci._ xli. 1901, p. 477.

[246] Loisel, _J. de l'Anat. et Phys._ xxxiv. 1898, p. 1.

[247] R. v. Lendenfeld, _Acta Ac. German._ lxix. 1896, p. 22.

[248] _Challenger Report_, lix. 1887, p. 214.

[249] Topsent, _Zoologie Descriptive_, i.; also Cotte, _C. R. Soc. Biol.

Paris_, 1902, pp. 638-639.

[250] Topsent, _Arch. Zool. Exp._ (3) viii. 1900, p. 36.

[251] Sollas, _Challenger Monograph_, xxv. pt. lxiii. 1888, p. lxxxix.

[252] Topsent, _Arch. Zool. Exp._ (3) viii. 1900, p. 226. For an account of

certain very remarkable structures termed diaphragms in _Cliona

mucronata_ and _C. ensifera_, see Sollas, _Ann. Mag. Nat. Hist._ (5)

i. 1878, p. 54.

[253] R. von Lendenfeld, _Monograph of Horny Sponges_, 1889, p. 831.

[254] Cf. Minchin in E. Ray Lankester's _Treatise_, p. 77.

[255] Maas, _Zool. Centralbl._ v. 1898, p. 581.

[256] _Arch. Zool. Exp._ viii. 1879, p. 59.

[257] "Biological Lectures, Wood's Holl," 1894, p. 43.

[258] F. E. Schulze, _Zool. Anz._ ii. 1879, p. 636.

[259] Maas, _Zeitschr. wiss. Zool._ lxx. 1901, p. 263.

[260] Maas, _loc. cit._ p. 284.

[261] _J. Coll. Japan_, xv. 1901, p. 180.

[262] Perkins, _Johns Hopkins Univ. Circ._ xxi. 1902, p. 87.

[263] For details of this interesting process see Minchin, _Quart. J. Micr.

Sci._ xl. 1898, p. 469.

[264] Maas, _Zeitschr. wiss. Zool._ lxvii. 1900, p. 225.

[265] Maas, _SB. Ak. München_, xxx. 1900, p. 553, and _Zeitschr. wiss.

Zool._ lxx. 1901, p. 265; see also Sollas, _Ann. Mag. Nat. Hist._ (5)

ix. 1880, p. 401.

[266] Sollas, _Challenger Monograph_, xxv. 1888, p. xlv.

[267] Sollas, _ibid._ pp. 13 and 34, pl. v.

[268] _Zeitschr. wiss. Zool._ lii. 1891, p. 294.

[269] I. Sollas, _P. Zool. Soc. London_, ii. 1902, p. 215.

[270] Sollas, _Ann. Mag. Nat. Hist._ (5) ix. 1880, p. 402.

[271] Bowerbank, and also Vosmaer and Pekelharing, _Verh. Ak. Amsterdam_

(2) vi. 3, 1898.

[272] _J. Coll. Japan_, xv. 1901, p. 193.

[273] Vosmaer and Pekelharing, _Verh. Ak. Amsterdam_, 1898.

[274] See Bidder, _P. Camb. Soc._ vi. 1888, p. 183; Sollas, _Challenger

Monograph_, xxv. 1883, pp. xviii.-xxi.; and Vosmaer and Pekelharing,

_loc. cit._

[275] Carter and Lieberkühn in 1856, Haeckel in 1872, Metschnikoff in 1879,

and many later workers.

[276] _Die Kalkschwämme_, 1872, i. p. 372.

[277] _J. Anat. Physiol._ 1898, pp. 1, 6, 234.

[278] _Mém. Ac. St. Pétersb._ (7) xxvi. 1878, p. 10.

[279] Sollas, _Challenger Report_, xxv. pt. lxiii. p. lxxxviii.

[280] _Vergl. Physiologie d. niederen Thiere_, 1903, p. 441.

[281] For further details see Zittel, _Lehrbuch der Palaeontologie_, and

Felix Bernard, _Eléments de Palaeontologie_, 1894.

[282] For further details see Sollas, "The Formation of Flints," in _The

Age of the Earth_, 1905, p. 131.

[283] _Willey's Zool. Results_, pt. ii. 1899, p. 127.

[284] Murbach, _Archiv f. Naturg._ lx. Bd. i. 1894, p. 217.

[285] G. H. Grosvenor, _Proc. Roy. Soc._ lxxii. 1903, p. 462.

[286] H. Jung, _Morph. Jahrb._ viii. 1881, p. 339.

[287] _Verh. Ver. Rheinland_, xlix. 1893, pp. 13, 14, 40, 41.

[288] For an account of the development and of the chitinous membrane see

A. Brauer, _Zeitschr. f. wiss. Zool._ lii. 1891, p. 9.

[289] Trembley, _Mémoires pour servir à l'Histoire d'un genre de Polypes

d'eau douce_, 1744.

[290] G. Wagner, _Quart. Journ. Micr. Sci._ xlviii. 1905, p. 589.

[291] See p. 126.

[292] _Hydra pallida_, Beardsley, has been found to be very destructive to

the fry of the Black-spotted Trout in Colorado, _U.S. Fish. Rep.

Bull._ 1902, p. 158.

[293] For figures of _Protohydra_ see Chun, Bronn's _Thier-Reich_,

"Coelenterata," 1894, Bd. ii. pl. ii.

[294] _Sitzber. Ges. naturf. Freunde Berlin_, ix. 1894, p. 226.

[295] M. Ussov, _Morph. Jahrb._ xii. 1887, p. 137.

[296] This organism is usually described as a fungus (_Achlya_), but it is

probably a green Alga. See J. E. Duerden, _Bull. Amer. Mus. Nat.

Hist._ xvi. 1902, p. 323.

[297] _Bibl. Univ. de Genève, Arch. des Sciences_, v. 1859, p. 80.

[298] _Phil. Trans._ cxlvii. 1876, p. 117.

[299] S. J. Hickson, _Willey's Zool. Results_, pt. ii. 1899, p. 127.

[300] _Quart. Journ. Micr. Sci._ xlii. 1899, p. 341.

[301] "Gymnoblastic Hydroids," _Ray Society_, 1871, p. 359.

[302] Hincks, _British Hydroid Zoophytes_, 1868, p. 74.

[303] _Ann. Mag. Nat. Hist._ (6) x. 1892, p. 207.

[304] Fewkes, _Bull. Mus. Comp. Zool._ xiii. 1887, p. 224.

[305] Hartlaub, _Wiss. Meeresunt. deutsch. Meere in Kiel_ N.F.I. 1894, p.

1.

[306] Carter, _Ann. Mag. Nat. Hist._ (4) xix. 1877, p. 44; (5) i. 1878, p.

298.

[307] The aberrant genus _Hypolytus_ (p. 262) may belong to this family.

[308] Spencer, _Trans. Roy. Soc. Vict._ 1892, p. 8.

[309] _Journ. Coll. Sci. Tokyo_, xiii. 1900, p. 235 (with a beautiful

coloured illustration).

[310] _Proc. Zool. Soc._ 1897, p. 818.

[311] _Zeitschr. f. wiss. Zool._ lxiii. 1898, p. 489.

[312] _Quart. Journ. Micr. Sci._ xlvi. 1902, p. 1.

[313] _Zool. Zentralbl._ x. 1903, p. 27.

[314] For a discussion of the origin of the polysiphonic stem in

Calyptoblastea see Nutting, "American Hydroids," _Smithsonian

Institution Special Bulletin_, pt. i. 1900, p. 4.

[315] _Loc. cit._ p. 33.

[316] The term "sarcostyle" is usually applied to the dactylozooid of the

Calyptoblastea.

[317] _Trans. Roy. Soc. Victoria_, 1890, p. 121.

[318] See C. C. Nutting, _Proc. U.S. National Museum_, xxi. 1899, p. 747.

[319] E. T. Browne, _Bergens Museums Aarbog_, 1903, iv. p. 18.

[320] Cf. Schepotieff, _Neues Jahrb. f. Mineralogie_, 1905, ii. pp. 79-98.

[321] S. J. Hickson and H. England, _Siboga Exped._ viii. 1904, p. 26.

[322] "Life-History of the Hydromedusae," _Mem. Boston Soc._ iii. 1885, p.

359.

[323] _Journ. Morph._ xi. 1895, p. 493.

[324] H. F. Perkins, _Proc. Acad. Nat. Sci. Phil._ Nov. 1902, p. 773.

[325] E. T. Browne, _Proc. Zool. Soc._ 1896, p. 495.

[326] _Mark Anniversary Volume_, New York, 1903, p. 1.

[327] C. Vaney et A. Conte, _Zool. Anz._ xxiv. 1901, p. 533.

[328] S. Goto, _l.c._

[329] G. H. Fowler, _Quart. Journ. Micr. Sci._ xxx. 1890, p. 507.

[330] _Limnocnida_ has recently been discovered by Budgett in the river

Niger. See Browne, _Ann. Nat. Hist._ xvii. 1906, p. 304.

[331] "The Tanganyika Problem," 1903, p. 298.

[332] Cf. Boulenger, Presidential Address to Section D of the British

Association (Cape Town, 1905).

[333] C. Hartlaub, _Verhandl. Deutsch. Zool. Ges_. 1896, p. 3.

[334] _Abh. Senckenb. Ges._ xvi. 1891, p. 44.

[335] This gas is frequently called air. The gas contained in the

pneumatophore of _Physalia_ was analysed by Schloessing and Richard,

_C. R._ cxxii. 1896, p. 615, and found to consist of CO_{2}, 1.7

parts, O 15.1, nitrogen and argon, 83.2.

[336] The chemical composition of the substance here called "chitin" has

not been accurately determined. An analysis of two specimens of

_Velella_ bladders gave 9.71 and 10.35 per cent of nitrogen, which is

higher than that of chitin and nearer to that of mucin.

[337] _Zool. Jahrb. Suppl._ 1904, p. 347.

[338] _Johns Hopkins Univ. Circ._ x. 1891, p. 91.

[339] C. Chun, _Abh. Senck. Nat. Ges. Frankfort_, xvi. 1891.

[340] Brooks and Conklin, _Johns Hopkins Univ. Circ._ x. 1891, No. 88.

[341] C. E. Borchgrevink, "First on the Antarctic Continent," 1901, p. 227.

[342] M. J. Delap, _Irish Naturalist_, x. 1901, p. 27.

[343] E. W. L. Holt, _Report on the Sea and Inland Fisheries of Ireland for

1902_, pt. ii. 1903, p. xvi.

[344] F. W. Gamble. See E. T. Browne, _Proc. Roy. Irish Acad._ 1900, p.

735.

[345] _Bull. Mus. Comp. Zool._ xxxii. 1, 1898.

[346] ἀκαλήφη = a nettle.

[347] _Biometrika_, i. 1901, p. 90.

[348] K. Kishinouye, _Zool. Jahrb. Syst._ xii. 1899, p. 206.

[349] For the discussion of this relationship the reader is referred to

Goette, _Zeitschr. wiss. Zool._ lxiii. 1897, p. 360, and Carlgren,

_Zool. Anz._ xxii. 1899, p. 31.

[350] See note ^{[347]}, above.

[351] E. A. Minchin, _Proc. Zool. Soc._ 1889, p. 583.

[352] For good illustrations of this see Sir J. Dalyell, "Rare and

Remarkable Animals of Scotland," vol. i. 1847, pll. 13, 14, 18, 19,

20.

[353] _Archiv. Mikr. Anat._ xiii. 1877, p. 795.

[354] Agassiz and Mayer, _Mem. Mus. Comp. Zool._ xxvi. 3, 1902, p. 153.

[355] F. S. Conant, _Mem. Johns Hopkins Univ._ iv. 1, 1898.

[356] Kishinouye, _Journ. Coll. Sci. Tokyo_, xvii. 7, 1902.

[357] A discussion of the classification of this order occurs in Vanhöffen,

"Acrasped. Med. d. deutschen Tiefsee Expedition," iii. 1902, p. 49.

[358] The Periphyllidae constitute Haeckel's order Peromedusae.

[359] A stage in development before the formation of the sub-umbrellar

cavity, but subsequent to the formation of the first tentacles, is

regarded as homologous with the Scyphistoma stage of other Scyphozoa.

[360] _"Siboga" Exped._ Mon. xi. 1903.

[361] _Proc. Roy. Irish Acad._ 3rd ser. v. 1900, p. 735.

[362] Cf. Darwin, _Voyage of the Beagle_, chap. v.

[363] Hickson, _K. Akad. Wet. Amsterdam_, 1905.

[364] J. H. Ashworth, _Proc. Roy. Soc._ lxiii. 1898, p. 443.

[365] _Quart. Journ. Micr. Sci._ xli. 1899, p. 521.

[366] Quoted by Hickson, _Marine Investigations, S. Africa_, iii. 1904, p.

215.

[367] G. C. Bourne, _Phil. Trans. Roy. Soc._ clxxxvi. 1895, B. p. 464.

[368] Quoted by Marshall, _Oban Pennatulida_, 1882, p. 49.

[369] _Quart. Journ. Micr. Sci._ xlix. 1905, p. 327.

[370] _Corallium nobile_ appears to be the exception to this rule, as it is

stated that colonies and even individual zooids are occasionally

hermaphrodite. Lacaze Duthiers, "Hist. Nat. du Corail," 1864, p. 127.

[371] G. Lindström, _Handl. k. Svensk. Vet. Akad._ xxxii. 1899.

[372] J. W. Gregory, _Proc. Roy. Soc._ lxvi. 1899, p. 291.

[373] G. C. Bourne, Lankester's _Treatise on Zoology_, pt. ii. 1900,

"Anthozoa," p. 26.

[374] E. M. Pratt, _Fauna and Geogr. Maldive Archip._ ii. pt. i. 1903, p.

516.

[375] _Zool. Anz._ xxix. 1905, p. 263.

[376] S. J. Hickson, _Fauna and Geog. Maldive Archip._ ii. pt. i. 1903, p.

495.

[377] Hickson, _K. Akad. Wet._ Amsterdam, 1905.

[378] _Journ. Imp. Fish. Bureau_, Tokyo, xiv. 1, 1904.

[379] Kitahara, _Journ. Imp. Fish. Bureau_, Tokyo, xiii. 3, 1904.

[380] Johnson, _Proc. Zool. Soc._ 1899, p. 57.

[381] Hickson, _Nature_, lxxiii. 1905, p. 5.

[382] Moroff, _Zool. Jahrb. Syst._ xvii. 1902, p. 404.

[383] Ridley, _Proc. Zool. Soc._ 1882, p. 231.

[384] For a revision of this family, see Versluys, _Siboga Expeditie_, xii.

1902.

[385] Jungersen (_Danish Ingolf Expedition_, Pennatulida, 1904) has shown

that this is the correct nomenclature of the regions of the rachis.

Nearly all other authors describe the dorsal side as ventral and the

ventral as dorsal.

[386] S. J. Hickson, _Report British Association_ (Southport Meeting),

1903, p. 688.

[387] Marshall, _Trans. Roy. Soc. Edinb._ xxxii. 1883, p. 143.

[388] Rumphius, _Amboinsche Rariteitkamer_, 1741, p. 64.

[389] Darwin, _Naturalist's Voyage round the World_, 1845, p. 99.

[390] To be described in the forthcoming Report on the Pennatulidae of the

"Siboga" Expedition.

[391] _Zool. Anz._ xxv. 1902, p. 302.

[392] Faurot, _Arch. Zool. Expér._ 3rd ser. iii. 1895, p. 71.

[393] Duerden, _Mem. Acad. Washington_, 3rd Ser. viii. 1902.

[394] Duerden, _l.c._ p. 436.

[395] M'Intosh, "The Marine Invertebrates and Fishes of St. Andrews," 1875,

pp. 37, 38.

[396] M'Intosh, "The Resources of the Sea," 1899, pp. 10, 129.

[397] H. Prouho, _Arch. Zool. Expér._ 2nd ser. ix. 1891, p. 247.

[398] Duerden, _Mem. Acad. Washington_, viii. 1902, p. 437.

[399] Ashworth and Annandale, _Proc. Roy. Soc. Edinb._ xxv. 1904, p. 11.

[400] For recent experiments on this case, see a forthcoming paper by J. E.

Duerden (_P.Z.S._).

[401] Saville Kent, "Great Barrier Reef," London, 1893, p. 145.

[402] O. Carlgren, _Biolog. Centralbl._ xxi. 1901, p. 480.

[403] Saville Kent, "The Great Barrier Reef," 1893, p. 144.

[404] A. C. Haddon, _Trans. Roy. Dubl. Soc._ iv. 1889, p. 325.

[405] G. H. Fowler, _Quart. Journ. Micr. Sci._ xxix. 1888, p. 143.

[406] For a general account of the Madreporarian skeleton, cf. Ogilvie,

_Phil. Trans. Roy. Soc._ clxxxvii. B. 1896.

[407] H. M. Bernard, _Ann. Mag. Nat. Hist._ (7) xiii. 1904, p. 1.

[408] "Report on the Results of Dredging on the Macclesfield Bank,"

_Admiralty Report_, 1894.

[409] C. Darwin, _Coral Reefs_, 3rd edition, 1889, p. 125.

[410] For the details of these borings, see "The Atoll of Funafuti," _Royal

Society of London_, 1904.

[411] For further information, see J. Stanley Gardiner, _The Fauna and

Geography of the Maldive and Laccadive-Archipelagoes_, vol. i. pt.

ii. 1902, p. 172.

[412] Saville Kent, "Great Barrier Reef," 1893, p. 185.

[413] Duerden, _Mem. Ac. Washington_, viii. 1902, p. 550.

[414] H. M. Bernard, _Journ. Linn. Soc. Zool._ xxvi. 1897, p. 495.

[415] E. M. Pratt, _Willey's Zoological Results_, pt. v. 1900, p. 591.

[416] G. H. Fowler, _Quart. Journ. Micr. Sci._ xxx. 1890, p. 410.

[417] J. E. Duerden, _Mem. Ac. Washington_, viii. 1902, p. 553.

[418] M. Ogilvie, _Trans. Roy. Soc._ clxxxvii. B. 1896.

[419] "The Coral _Siderastraea_," _Carnegie Inst._ No. 20, Washington,

1904.

[420] The reader is referred to the excellent photographs of living Fungias

in Saville Kent's "Great Barrier Reef," 1893, pl. xxiv. p. 160.

[421] _Trans. Roy. Soc. Dubl._ (2) vi. 1898, p. 331.

[422] F. J. Bell, _Trans. Zool. Soc._ xiii. pt. ii. 1891, p. 87.

[423] J. E. Duerden, _Ann. Mag. Nat. Hist._ (7) ix. 1902, p. 381.

[424] Hickson, _Nature_, lxxiii. 1905, p. 5.

[425] L. Roule, _Bull. Mus. Océanogr. Monaco_, 1904, p. 3.

[426] E. van Beneden, _Les Anthozoaires de la Plankton Expédition_, Kiel,

1898.

[427] A. W. Peters, _Journ. Exper. Zool._ ii. (1) 1905, p. 103.

[428] Cnidoblasts are stated by Chun to occur on the tentacles of

_Euchlora_; and batteries of "nettle cells" by Abbott on the

tentacles of _Coeloplana_.

[429] The two costae that are seen in the middle when the Ctenophore is

viewed in the transverse plane, as in Figs. 180 and 181, and the

corresponding costae on the opposite side are called the "transverse"

costae; the other four are called the "sagittal" costae.

[430] F. Mosser, "Ctenophoren de Siboga Expedition," Leiden, 1903.

[431] H. B. Bigelow, _Bull. Mus. Comp. Zool._ xxxix. 1904, p. 267.

[432] _Quart. Journ. Micr. Sci._ xxxix. 1897, p. 323.

[433] _Annot. Zoolog. Japon._ iv. pt. iv. 1902, p. 103.

[434] Abbott, _l.c._ p. 106.

[435] _Zool. Anz._ xxvii. 1904, p. 223.

[436] The name seems first to have been used by Klein in 1734, "Naturalis

dispositio Echinodermatum" (Danzig). Leuckart about 1850 first

established Echinodermata as a primary division of the animal

kingdom.

[437] In the Synaptidae the radial canals although present in the young are

lost in the adult (Ludwig, 1892, in Bronn's _Thier-Reich_, Bd. ii.

Abt. 3, Buch i. p. 460).

[438] Ludwig, _loc. cit._ p. 357.

[439] This classification is substantially that suggested by Jeffrey Bell,

_Catalogue of British Echinoderms in the British Museum_, 1892,

except that Bell separates Holothuroidea from all others. Reasons

will be given later for regarding Holothuroidea as modified

Echinoidea.

[440] Gr. ἀστήρ, a "star"; εἶδος, "form." Linnaeus established the genus

_Asterias_ in 1766. Johannes Müller in 1842 used the name

"Asteriden," and in _System der Asteriden_, 1842, by Müller and

Troschel, the foundation of our knowledge of the group was laid.

[441] Uexküll, "Die Physiologie der Pedicellarien," _Zeitschr. f. Biol._

xxxvii. 1899, p. 356.

[442] Durham, "Wandering Cells in Echinodermata," _Quart. J. Micr. Sci._

xxxiii. 1891, pp. 81 _et seq._

[443] Starfish are most destructive on oyster-beds, and hence possess

considerable negative economic value.

[444] _Mitth. des deutschen Seefischervereins_, xii. 1896, p. 102, and _J.

Mar. Biol. Ass._ iv. 1895-97, p. 266.

[445] Romanes, "Jellyfish, Starfish, and Sea Urchins," _Intern. Scientific

Series_, 1885, pp. 320, 321; Preyer, "Bewegungen von Stelleriden,"

_Mitth. Zool. Stat. Neapel_, vii. 1886-87, p. 22.

[446] Preyer, _loc. cit._ p. 49.

[447] Bronn's _Thier-Reich_, Bd. ii. Abt. 3, Buch ii. Seesterne, p. 617.

[448] _Beiträge zur Histologie der Echinodermen_, Jena, 1889. Such spaces

are always to be seen in _Asterina gibbosa_ when preserved with

corrosive sublimate or other acid reagents, but are absent when it is

preserved with osmic acid and Mueller's fluid. Though corrosive

sublimate is usually regarded as a neutral salt, its aqueous solution

decomposes with the production of a certain amount of free

hydrochloric acid.

[449] "Beiträge zur Anatomie der Asteriden," _Zeitschr. wiss. Zool._ xxx.

1877, pp. 122 _et seq._

[450] "Cont. à l'Étude anat. des Astérides," _Arch. Zool. Exp._ (2) v.

_bis_, 1887, p. 104.

[451] The analogy of Echinoidea (see p. 529) might suggest that, like the

lacteals in man, these strands were channels along which the products

of digestion diffused outward. No connexion, however, between the

oral ring and the alimentary canal has been made out, nor do there

appear to be such strands developed in the proximity of the wall of

the digestive tube. A connexion between the aboral ring and the

rectum through a mesenteric cord has been asserted, but this is

doubtful.

[452] "Die Echinodermen des Golfes von Neapel," _Fauna u. Flora G. von

Neapel_, xxiv. Monogr. 1897, pp. 349-351.

[453] Ludwig, "Die Echinodermen des Golfes von Neapel," pp. 68, 69.

[454] Ludwig, "Scientific Results of the Expedition of the 'Albatross' to

the Tropical Pacific"—"Asteroidea," 1905, pp. 91, 103.

[455] _Rés. sci. Expéd. Travailleur et Talisman_, "Échinodermes," 1894, pp.

10-15.

[456] Schiemenz (reference on p. 440 n.).

[457] This fact was discovered by Dr. E. J. Allen, Director of the Plymouth

Biological Station, who pointed it out to the author during the

latter's sojourn at the station in 1899.

[458] This figure does not show the animal's attitude during forward

progression quite correctly. The tips of the two anterior arms should

be bent outwards, not inwards as in the figure.

[459] In the more primitive Ophiuroidea (Streptophiurae) it persists all

over the body; in Cladophiurae it is found on the central part of the

disc.

[460] How far this form of respiratory mechanism is distributed amongst

Ophiurids it is impossible to say. It was first observed by me in the

case of _Ophiothrix fragilis_ at Plymouth in 1905, but since then I

have found it in _Ophiura ciliaris_ and in _Amphiura squamata_.

[461] "Neue Beitr. zur Anat. d. Ophiuriden," _Zeitschr. wiss. Zool._ xxxiv.

1880, p. 340.

[462] "Bewegungen d. Seesternen," _Mitth. Zool. Stat. Neapel_, vii.

1886-87, p. 123.

[463] Bell, "Contribution to the Classification of Ophiuroids," _Proc.

Zool. Soc._ 1892, p. 175.

[464] Hamann, _Bronn's Thier-Reich_, Bd. ii. Abt. 3, Ophiuroidea, 1900, p.

910 f., discriminates a family Ophiodermatidae, but gives no

character by which it can be distinguished from Ophiolepididae.

[465] Forbes, "A History of British Starfishes and other animals of the

class Echinodermata," 1841, p. 23.

[466] Simroth, "Anatomie und Schizogonie der _Ophiactis virens_,"

_Zeitschr. wiss. Zool._ xxvii. 1876, p. 452.

[467] Cuénot, "Études Morphologiques sur les Echinodermes," _Arch.

Biologie_, xi. 1891, pp. 568 _et seq._

[468] This type of mouth-frame is represented in Fig. 215, A, by a figure

of _Ophioscolex_, which belongs to the Streptophiurae.

[469] "Asteriden und Ophiuriden aus dem Silur Böhmens," _Zeitschr. der

deutschen geol. Ges._ lv. 1903, pp. 106-113 (Protokolle).

[470] _Geol. Magazine_, No. 490, April 1905, pp. 161-168.

[471] "Die Physiologie des Seeigelstachels," _Zeitschr. für Biol._ xxxix.

1900, pp. 73 _et seq._

[472] Uexküll, "Die Physiologie der Pedicellarien," _Zeitschr. für Biol._

xxxvii. 1899, p. 334.

[473] "Du rôle des pédicellaires gemmiformes des Oursins," _Compt. Rend.

Acad. de Paris_, cxi. 1890, pp. 62-64.

[474] "The Fauna and Bottom Deposits near the thirty-fathom line from the

Eddystone grounds to Startpoint," _Journ. Marine Biol. Ass._ v. 1899,

p. 472.

[475] "Mitth. über die zool. Stat. v. Neapel," _Zeitschr. wiss. Zool._ xxv.

1875, p. 471.

[476] Cuénot, "Études Morphologiques sur les Échinodermes," _Arch. Biol._

xi. 1891, p. 544.

[477] "Jellyfish, Starfish, and Sea-urchins," _Intern. Sci. Series_, 1885,

p. 302 _et seq._

[478] "Die Physiologie des Seeigelstachels," _Zeitschr. für Biol._ xxxix.

p. 73.

[479] "Bewegungen von Stelleriden," _Mitth. Zool. Stat. Neapel_, vii.

1886-7, p. 22.

[480] _Loc. cit._

[481] See note on p. 541.

[482] "Die Wirkung von Licht und Schatten auf die Seeigel," _Zeitschr. für

Biol._ xl. 1900, p. 447.

[483] In the aberrant genus _Asthenosoma_, where there are internal radial

muscles, there is also an internal series of nerve-cells on the

radial cord.

[484] We prefer the term "compasses," to avoid confusion with the other

meanings of the word "radius."

[485] "Ueber die Function der Polischen Blasen am Kauapparat der regulären

Seeigel," _Mitth. Zool. Stat. Neapel_, xii. 1897, p. 464.

[486] _Ergebnisse naturwissenschaftlicher Forschungen auf Ceylon_,

1887-1888, Bd. i. Heft 3, pp. 105 _et seq._

[487] "Das angebliche Excretionsorgan der Seeigel," _Zeitschr. wiss. Zool._

lv. 1893, p. 585.

[488] In this case the fluid flows from the lantern coelom into Stewart's

organs and _vice versa_. Oxygen must be absorbed through the

peristome. The Cidaridae are not as sensitive to want of oxygen as

the other families (Uexküll, _loc. cit._).

[489] _Danish Ingolf Expedition_, "Echinoidea," pt. i. 1903.

[490] Prouho, "Recherches sur le _Dorocidaris papillata_ et quelques autres

Échinides de la Méditerranée," _Arch. Zool. Exp._ (2) v. 1887, p.

308.

[491] "Revision of the Echini," _Illustrated Catalogue of Museum of Comp.

Zool. Harvard_, No. 7, 1874, p. 423.

[492] _British Museum Catalogue_, "British Echinoderms," 1892, p. 30.

[493] _Loc. cit._

[494] _Loc. cit._

[495] Reference on p. 528 n.

[496] This account of the periproct is different from that ordinarily

given. It is based on the most recent examination of this

family—Agassiz, "Panamic Deep-sea Echini," _Mem. Mus. Comp. Zool._

xxxi. 1904, p. 36.

[497] "Der Schatten als Reiz für _Centrostephanus longispinus_," _Zeitschr.

für Biol._ xxxiv. 1896, p. 319.

[498] Reference on p. 532, note [489].

[499] Mr. E. W. L. Holt, Scientific Adviser to the Irish Board of

Fisheries, casts doubt (_in litt._) on much of this supposed

excavation. While disclaiming any novelty in this observation, he

points out that in many cases one side of the cavity is formed by

calcareous algae, and it seems as if the animal wanders into a

crevice, in which it is imprisoned by the growth of this plant.

[500] These statements are based on the author's observations of the animal

in the Bay of Fundy in 1900.

[501] Lovén, "On a recent Form of Echinoconidae," _Bih. Svenska Akad.

Hand._ xiii. Af. 4, No. 10, 1889.

[502] Details were given to the author in conversation with Dr. Robertson

in 1896.

[503] This family includes three families discriminated by Meissner

(Bronn's _Thier-Reich_, vol. ii. Abt. 3, Buch iv. "Die Seeigel,"

1904, p. 402), viz.: Ananchytidae, Pourtalesiidae, and Urechinidae.

They only differ in the pores for the tube-feet, which are paired in

the first, slit-like and single in the second, and single in the

third.

[504] "On Silurian Echinoidea and Ophiuroidea," _Quart. Journ. Geol. Soc._

lv. 1899, pp. 701 _et seq._

[505] "The Metamorphosis of Echinoderms," _Quart. J. Micr. Sci._ xxxviii.

1896, p. 53.

[506] _Pelagothuria_ is said to have no calcifications.

[507] Hjalmar Théel, "On a singular Case of Hermaphroditism in

Holothurids," _Bih. Svenska Vet. Akad. Hand._ xxvii. Af. 4, No. 6,

1901.

[508] Bronn's _Thier-Reich_, vol. ii. Abt. 3, Buch i. "Die Seewalzen,"

1891, pp. 327 _et seq._

[509] Genuine suckers appear never to be developed; but the ends of the

ventral podia are sometimes rounded, sometimes slightly flattened.

[510] "Mémoire sur l'_Elpidia_ nouveau genre d'Holothuries," _K. Sv. Vet.

Akad._ xiv. No. 8, 1877.

[511] Gerould, "The Anatomy and Histology of _Caudina armata_," _Bull. Mus.

Comp. Zool._ No. 56, 1895, p. 124.

[512] "Structure, Physiology, and Development of _Antedon rosaceus_,"

_Phil. Trans. Roy. Soc._ 1866, pp. 671-756.

[513] "On the Nervous System of _Antedon rosaceus_," _Q.J.M.S._ xxiv. 1884,

p. 507.

[514] Bather calls the side-plates "adambulacral." The name is unfortunate,

as it suggests that the side-plates correspond to the adambulacrals

of Asteroidea; but when the groove is closed the position and

function of adambulacrals and covering plates is the same

(Lankester's _Treatise on Zoology_, iii. "Echinodermata," 1900).

[515] _Challenger Reports_ (_Stalked Crinoids_), vol. xi. pt. xxxii. 1884.

[516] _Stammesgeschichte der Pelmatozoen_, pt. i. 1899.

[517] "Die Echinodermenlarven der Plankton Expedition," _Ergebn. Plankton

Exp._ Bd. ii. J, 1898.

[518] "Über die Larvenzustande und die Metamorphose der Ophiuren und

Seeigel," _Abh. K. Akad. wiss. Berlin_, 1846, and other papers in the

same publication in subsequent years.

[519] This is clearly seen by comparing the larva of _Asterina gibbosa_

with a young Bipinnaria in which the longitudinal band is as yet

undivided. The shape of the prae-oral lobe is practically the same in

both.

[520] "The Fate of the Body-cavities in the Metamorphosis of _Asterias

pallida_," J. _Coll. Japan_, x. 1898, p. 239.

[521] Yves Delage, "Elevage des Larves parthénogénétiques _d'Asterias

glacialis_," _Arch. Zool. Exp._ (4) ii. 1904, p. 27.

[522] "The Metamorphosis of Echinoderms," _Quart. Journ. Micr. Sc._

xxxviii. 1895, p. 45.

[523] In the type figured (larva of _Synapta digitata_) the feelers are

budded off directly from the ring-canal and alternate with the

rudiments of the radial canal.

[524] Observed in Plymouth, 1905.

[525] "Die Entwicklung der _Synapta digitata_," _Jen. Zeitschr._ xxii.

1888, p. 175.

[526] "Die Cambrische Stammgruppe der Echinodermen," _Jen. Zeitschr._ xxx.

1895.

[527] Lankester's _Treatise on Zoology_, "Echinodermata," pt. iii. 1900, p.

33.

[528] _Brit. Mus. Cat._ "British Echinodermata," 1892, p. 14.

* * * * *

Corrections made to printed text