[1] Garcilasso de la Vega, writing of the plant, says that it is
called _cuca_ by the Indians, _coca_ by the Spaniards; and Father
Blas Valera states that the leaves are called _cuca_ both by Indians
and Spaniards (_The Royal Commentaries of the Yncas_, 1609-1617;
trans, by C. R. Markham, Hakluyt Soc., 1871). See also, on the name
_cuca_, Christison, _Brit. Med. Journ._, April 29, 1876, p. 527.
COCAINE, C17H21NO4, an alkaloid occurring to the extent of about 1% in
the leaves of _Erythroxylon coca_ (see above). It is associated with
many other alkaloids: cinnamyl cocaine, C19H23NO4; [alpha]-truxilline,
(C19H23NO4)2; [beta]-truxilline, (C19H23NO4)2; benzoylecgonine,
C16H19NO2; tropa-cocaine, C15H19NO2; hygrine, C8H15NO; cuscohygrine,
C13H24NO2. These substances, which may be collectively termed
"cocaines," are all derivatives of ecgonine (q.v.). Cocaine is
benzoylmethyl ecgonine. It crystallizes from alcohol in prisms, which
are sparingly soluble in water. Its solution has a bitter taste,
alkaline reaction, and is laevorotatory. Its use as a local anaesthetic
(see ANAESTHESIA) makes it the most valuable of the coca alkaloids, and
it is much used in ophthalmic practice. Applied to the conjunctiva it
causes anaesthesia, dilatation of the pupil, diminution of the
intraocular tension, and some interference with accommodation. The
conversion of the mixture obtained by extracting coca-leaves into
cocaine is effected by saponifying the esters into ecgonine and the
respective acids, and then benzoylating and methylating the ecgonine.
Homologues of cocaine--ethylbenzoylecgonine, &c.--have been prepared;
they closely resemble natural cocaine. Cinnamyl cocaine is
cinnamylmethylecgonine, i.e. cocaine in which the benzoyl group is
replaced by the cinnamyl group. [alpha]- and [beta]-truxillines, named
from their isolation from a coca of Truxillo (Peru), are two isomeric
alkaloids which hydrolyse to ecgonine, methyl alcohol, and two isomeric
acids, the truxillic acids, C18H16O4. The alkaloids are therefore methyl
truxillylecgonines. The truxillic acids have been studied by K.
Liebermann and his students (_Ber._, vols. 21-27, and 31), and are
diphenyl tetramethylene dicarboxylic acids.
COCANADA, or COCONADA, a town of British India, in the Godavari district
of Madras, on the coast in the extreme north of the Godavari delta,
about 315 m. N. of Madras. Pop. (1901) 48,096, showing an increase of
18% in the decade. As the administrative headquarters of the district,
and the chief port on the Coromandel coast after Madras, Cocanada was
formerly of considerable importance, but its shipping trade has
declined, owing to the silting of the anchorage, and to the construction
of the railway. It is connected by navigable channels with the canal
system of the Godavari delta, and by a branch line with Samalkot on the
East Coast railway. The anchorage is an open roadstead, with two
lighthouses. The chief exports are rice, cotton, sugar and oilseeds.
Mills have been established for cleaning rice. The town contains a
second-grade college, a high school, and a literary association.
COCCEIUS [strictly KOCH], JOHANNES (1603-1669), Dutch theologian, was
born at Bremen. After studying at Hamburg and Franeker, where Sixtinus
Amama was one of his teachers, he became in 1630 professor of biblical
philology at the "Gymnasium illustre" in his native town. In 1636 he was
transferred to Franeker, where he held the chair of Hebrew, and from
1643 the chair of theology also, until 1650, when he succeeded Fr.
Spanheim the elder as professor of theology at Leiden. He died on the
4th of November 1669. His chief services as an oriental scholar were in
the department of Hebrew philology and exegesis. As one of the leading
exponents of the "covenant" or "federal" theology, he spiritualized the
Hebrew scriptures to such an extent that it was said that Cocceius found
Christ everywhere in the Old Testament and Hugo Grotius found him
nowhere. He taught that before the Fall, as much as after it, the
relation between God and man was a covenant. The first covenant was a
"Covenant of Works." For this was substituted, after the Fall, the
"Covenant of Grace," to fulfil which the coming of Jesus Christ was
necessary. He held millenarian views, and was the founder of a school of
theologians who were called after him Cocceians. His theology was
founded entirely on the Bible, and he did much to promote and encourage
the study of the original text. In one of his essays he contends that
the observance of the Sabbath, though expedient, is not binding upon
Christians, since it was a Jewish institution. His most distinguished
pupil was the celebrated Campeius Vitringa. His most valuable work was
his _Lexicon et Commentarius Sermonis Hebraici et Chaldaici_ (Leiden,
1669), which has been frequently republished; his theology is fully
expounded in his _Summa Doctrinae de Foedere et Testamento Dei_ (1648).
His collected works were published in 12 folio volumes (Amsterdam,
1673-1675). See Herzog-Hauck, _Realencyklopadie_.
COCCIDIA, an important order of Sporozoa Ectospora, parasites possessing
certain very distinctive characters. With one or two possible
exceptions, they are invariably intracellular during the entire trophic
life of the individual. They always attack tissue-cells, usually of an
epithelium, and never blood-corpuscles. Correlated with the advanced
degree of parasitism, there is a complete absence of specialization or
differentiation of the cell-body, and the trophozoite is quite incapable
of any kind of movement. In all cases, so far as known, the life-cycle
is digenetic, an asexual generation (produced by schizogony) alternating
with a sexual one (gametogony). After conjugation of two
highly-differentiated gametes has taken place, a resistant oocyst is
formed, which provides for the dispersal of the species; inside this
sporogony (spore- and sporozoite-formation) goes on.
History.
Hake (1839) was, perhaps, the first to describe a Coccidian, but he
regarded the parasites as pathological cell-products. In 1845 N.
Lieberkuhn pointed out the resemblances to Gregarines, with which
organisms he considered Coccidia to be allied. A year later, H. Kloss
proved the existence of similar parasites in the snail, and attempted to
construct their life-history; this form was subsequently named _Klossia
helicina_ by A. Schneider. The asexual part of the life-cycle was first
described by Th. Eimer in 1870, for a Coccidian infesting the mouse,
which was afterwards elevated by Schneider into a distinct genus
_Eimeria_. The generic name _Coccidium_ was introduced by R. Leuckart in
1879, for the parasite of the rabbit. It was many years, however, before
the double character of the life-cycle was realized, and the ideas of L.
and R. Pfeiffer, who first suggested the possibility of an alternation
of generations, for a long time found no favour. In the first decade of
the 20th century great progress was accomplished, thanks largely to the
researches of F. Schaudinn and M. Siedlecki, who first demonstrated the
occurrence of sexual conjugation in the group; and the Coccidian
life-history is now one of the best known among Sporozoa.
Habitat: effects on host.
Coccidia appear to be confined[1] to four great phyla, Vertebrates,
Molluscs, Arthropods and Annelids; the first named group furnishes by
far the most hosts, the parasites being frequently met with in domestic
animals, both birds and mammals. Following from the casual method of
infection, the epithelium of the gut or of its appendages (e.g. the
liver [Plate I., fig. 1]) is a very common seat of the parasitic
invasion. But in many cases Coccidia are found in other organs, to which
they are doubtless carried by lymphatic or circulatory channels. In
Molluscs, they often occur in the kidneys (fig. 2); in Insects, they are
met with as "coelomic" parasites, the fat-bodies, pericardial cells,
&c., being a favourite habitat; even the testis is not free from their
attentions in one or two instances, though the ovary appears always
immune.
The parasite invariably destroys its host-cell completely. The latter is
at first stimulated to abnormal growth and activity and becomes greatly
hypertrophied, the nucleus also undergoing karyolytic changes (fig. 4).
The fatty materials elaborated by the host-cell are rapidly used up by
the Coccidian, as nourishment; and at length the weakened and
disorganized cell is no longer able to assimilate but dies and is
gradually absorbed by the parasite, becoming reduced to a mere enclosing
skin or envelope. In some cases (ex. _Cyclospora caryolytica_ of the
mole) the parasite is actually intranuclear, the nucleus becoming
greatly swollen and transformed into a huge vacuole containing it.
The effects of a Coccidian infection upon the host as a whole depend
largely upon the extent to which endogenous multiplication of the
parasites takes place. On the one hand, schizogony may be so limited in
extent as not to cause appreciable injury to the host. This seems to be
often the case in forms infecting Molluscs and Arthropods. On the other
hand, where schizogony is rapid and prolonged, the results are often
serious. For, although any one individual only causes the death of a
single host-cell, yet the number of the parasites may be so enormously
increased by this means, that the entire affected epithelium may be
overrun and destroyed. Thus are occasioned grave attacks of coccidiosis,
characterized by severe enteritis and diarrhoea, which may end fatally.
In the case of the Vertebrates, secondary causes, resulting from the
stoppage of the bile ducts, also help to produce death. There is,
however, one factor in the endangered animal's favour. Schizogony cannot
go on indefinitely; it has a limit, dependent upon the supply of
host-cells, and consequently of nutriment, available. As this shows
signs of becoming exhausted, by the rapid multiplication of the
parasites, the latter begin to make preparations for the exogenous
cycle, inaugurated by gametogony. When conjugation has taken place and
sporogony is begun, the danger to the host is at an end. So that, if the
acute stage of the disease is once successfully passed, the regenerative
capacity of the epithelium may be able to restore something like
equilibrium to the deranged metabolism in time to prevent collapse.
Morphology and life-history.
_Coccidium schubergi_, parasitic in the intestine of a centipede
(_Lithobius forficatus_), may be taken as an example of a Coccidian
life-history (see Schaudinn, 1900): some of the more important
variations exhibited by other forms will be noted afterwards. The
trophozoite, or actively-growing parasite, is an oval or rounded body
(fig. 3, I.). The general cytoplasm shows no differentiation into
ectoplasm and endoplasm; it is uniformly alveolar in character. The
nucleus is relatively large, and possesses a distinct membrane and a
well-marked reticulum in which are embedded grains of chromatin. Its
most conspicuous feature is the large deeply-staining karyosome, which
consists of the greater part of the chromatin of the nucleus intimately
bound up with a plastinoid basis. When fully grown, the trophozoite (now
a schizont) undergoes schizogony. Its nucleus divides successively to
form a number of nuclei, which travel to the periphery, and there become
more or less regularly disposed (fig. 3, II. and III.). The protoplasm
in the neighbourhood of each next grows out, as a projecting bud,
carrying the nucleus with it. In this manner are formed a number of
club-shaped bodies, the merozoites, which are at length set free from
the parent-body (IV.), leaving a certain amount of residual cytoplasm
behind. By the rupture of the disorganized host-cell,[2] the
fully-formed merozoites are liberated into the intestinal lumen, and
seek out fresh epithelial cells. Each is more or less sickle-shaped, and
capable of active movements. Once inside a new host-cell, the merozoite
grows to a schizont again.
After this course has been repeated several times, gametogony sets in,
the trophozoites growing more slowly and becoming the parent-cells of
the sexual elements (gametocytes), either male individuals
(microgametocytes) or female ones (megagametocytes). A microgametocyte
(fig. 3, VI. [mars]) is characterized by its dense but finely reticular
or alveolar cytoplasm, very different from the loose structure of that
of a schizont. The male elements (microgametes) are formed in a manner
essentially comparable to that in which the formation of merozoites
takes place. Although the details of the nuclear changes and divisions
vary somewhat, the end-result is similar, a number of little nuclear
agglomerations being evenly distributed at the surface (VII. [mars])
Each of these elongates considerably, becoming comma-shaped and
projecting from the gametocyte. Nearly all the body of the male gamete
(VIII. [mars]) consists of chromatin, the cytoplasm only forming a very
delicate zone or envelope around the nucleus. From the cytoplasm two
long fine flagella grow out, one of which originates at the anterior
end, the other, apparently, at the hinder end, acting as a rudder; but
it is probable that this also is developed at the anterior end and
attached to the side of the body. By means of their flagella the
numerous microgametes break loose from the body of the microgametocyte
and swim away in search of a female element.
A megagametocyte (VI. [venus]) is distinguished by its rather different
shape, being more like a bean than a sphere until ripe for maturation,
and by the fact that it stores up in its cytoplasm quantities of reserve
nutriment in the form of rounded refringent plastinoid grains. Each
female gametocyte gives rise to only a single female element
(megagamete), after a process of nuclear purification. The karyosome is
expelled from the nucleus into the cytoplasm, where it breaks up at once
into fragments (VII. [venus]). Meanwhile the gametocyte is becoming
spherical, and its changes in shape aid in setting it free from the
shrivelled host-cell. The fragments of the karyosome, which are, as it
were, squeezed out to the exterior, exert a powerful attraction upon the
microgametes, many of which swarm round the now mature megagamete. The
female nucleus (pronucleus) approaches the surface of the cell (VIII.
[venus]), and at this spot a little clear cytoplasmic prominence arises
(cone of reception). On coming into contact with this protuberance
(probably attracted to it by the female pronucleus), a microgamete
adheres. Partly by its own movements and partly by the withdrawal of the
cone of attraction, the male penetrates into the female element and
fertilization is accomplished. Only one microgamete can thus pass into
the megagamete, for immediately its entry is effected a delicate
membrane is secreted around the copula (zygote), which effectually
excludes other less fortunate ones. This membrane rapidly increases in
thickness and becomes the oocyst (IX.), and the copula is now ready to
begin sporogony.
Sporogony goes on indifferently either inside the host or after the cyst
has been passed out with the faeces to the exterior. The definitive
nucleus of the zygote (resulting from the intimate fusion of the male and
female pronuclei, by means of a somewhat elaborate "fertilization-spindle"
[X.]) gives rise by successive direct divisions to four nuclei (XII.),
around which the protoplasm becomes segregated; these segments form the
four sporoblasts. Around each sporoblast two membranes are successively
secreted (exospore and endospore), which constitute the sporocyst (XIII.);
the sporocyst and its contents forming the spore. The nucleus of each
spore next divides, again directly, and this is followed by the division
of the cytoplasm. As a final result, each of the four spores contains two
germs (sporozoites), and a certain amount of residual protoplasm (fig. 3,
XIV.); this latter encloses a viscid, vacuole-like body, which aids in the
subsequent dehiscence of the sporocyst. On being eaten by a fresh host,
the wall of the oocyst is dissolved at a particular region by the
digestive juices, which are thus enabled to reach the spores and cause the
rupture of the sporocysts. As the result of instructive experiments,
Metzner has shown that it is the pancreatic and not the gastric juice by
which this liberation of the germs is effected. The liberated sporozoites
creep out and proceed to infect the epithelial cells. The sporozoites
(XV.) are from 15-20 [mu] long by 4-6 [mu] wide; they are fairly similar to
merozoites in form, structure and behaviour, the chief point of
distinction being that they have no karyosome in the nucleus (cf. above).