separation of a mass from the parent (germ-plasm) which under certain
conditions grows into an individual resembling the parent. The goal of
the study of heredity will be reached only when all the phenomena can be
referred to the nature of the germ-plasm and of its relations to the
conditions under which it grows, but we have seen how far our knowledge
is from any attempt at such references. In the meantime, the empirical
facts, the actual relations of the characters in the offspring to the
characters of the parents and ancestors, are being collected and
grouped. In this inquiry it at once becomes obvious that every character
found in a parent may or may not be present in the offspring. When any
character occurs in both, it is generally spoken of as transmissible and
of having been transmitted. In this broad sense there is no character
that is not transmissible. In all kinds of reproduction, the characters
of the class, family, genus, species, variety or race, and of the actual
individual, are transmissible, the certainty with which any character
appears being almost in direct proportion to its rank in the descending
scale from order to individual. The transmitted characters are
anatomical, down to the most minute detail; physiological, including
such phenomena as diatheses, timbre of voice and even compound
phenomena, such as _gaucherie_ and peculiarity of handwriting;
psychological; pathological; teratological, such as syndactylism and all
kinds of individual variations. Either sex may transmit characters which
in themselves are necessarily latent, as, for instance, a bull may
transmit a good milking strain. In forms of asexual reproduction, such
as division, budding, propagation by slips and so forth, every character
of the parent may appear in the descendant, and apparently even in the
descendants produced from that descendant by the ordinary sexual
processes. In reproduction by spore formation, in parthenogenesis and in
ordinary sexual modes, where there is an embryological history between
the separated mass and the new adult, it is necessary to attempt a
difficult discrimination between acquired and innate characters.
_Acquired Characters._--Every character is the result of two sets of
factors, those resident in the germinal material and those imposed from
without. Our knowledge has taken us far beyond any such idea as the
formation of a germinal material by the collection of particles from the
adult organs and tissues (gemmules of C. Darwin). The inheritance of any
character means the transmission in the germinal material of matter
which, brought under the necessary external conditions, develops into
the character of the parent. There is necessarily an acquired or
epigenetic side to every character; but there is nothing in our
knowledge of the actual processes to make necessary or even probable the
supposition that the result of that factor in one generation appears in
the germ-plasm of the subsequent generations, in those cases where an
embryological development separates parent and offspring. The
development of any normal, so-called "innate," character, such as, say,
the assumption of the normal human shape and relations of the frontal
bone, requires the co-operation of many factors external to the
developing embryo, and the absence of abnormal distorting factors. When
we say that such an innate character is transmitted, we mean only that
the germ-plasm has such a constitution that, in the presence of the
epigenetic factors and the absence of abnormal epigenetic factors, the
bone will appear in due course and in due form. If an abnormal
epigenetic factor be applied during development, whether to the embryo
_in utero_, to the developing child, or in after life, abnormality of
some kind will appear in the bone, and such an abnormality is a good
type of what is spoken of as an "acquired" character. Naturally such a
character varies with the external stimulus and the nature of the
material to which the stimulus is applied, and probability and
observation lead us to suppose that as the germ-plasm of the offspring
is similar to that of the parent, being a mass separated from the
parent, abnormal epigenetic influences would produce results on the
offspring similar to those which they produced on the parent. Scrutiny
of very many cases of the supposed inheritance of acquired characters
shows that they may be explained in this fashion--that is to say, that
they do not necessarily involve any feature different in kind from what
we understand to occur in normal development. The effects of increased
use or of disuse on organs or tissues, the reactions of living tissues
to various external influences, to bacteria, to bacterial or other
toxins, or to different conditions of respiration, nutrition and so
forth, we know empirically to be different in the case of different
individuals, and we may expect that when the living matter of a parent
responds in a certain way to a certain external stimulus, the living
matter of the descendant will respond to similar circumstances in a
similar fashion. The operation of similar influences on similar material
accounts for a large proportion of the facts. In the important case of
the transmission of disease from parent to offspring it is plain that
three sets of normal factors may operate, and other cases of
transmission must be subjected to similar scrutiny: (1) a child may
inherit the anatomical and physiological constitution of either parent,
and with that a special liability of failure to resist the attacks of a
widespread disease; (2) the actual bacteria may be contained in the ovum
or possibly in the spermatozoon; (3) the toxins of the disease may have
affected the ovum, or the spermatozoon, or through the placenta the
growing embryo. Obviously in the first two cases the offspring cannot be
said in any strict sense to have inherited the disease; in the last
case, the theoretical nomenclature is more doubtful, but it is at least
plain that no inexplicable factor is involved.
It is to be noticed, however, that "Lamarckians" and "Neo-Lamarckians"
in their advocacy of an inheritance of "acquired characters" make a
theoretical assumption of a different kind, which applies equally to
"acquired" and to "innate" characters. They suppose that the result of
the epigenetic factors is reflected on the germ-plasm in such a mode
that in development the products would display the same or a similar
character without the co-operation of the epigenetic factors on the new
individual, or would display the result in an accentuated form if with
the renewed co-operation of the external factors. Such an assumption
presents its greatest theoretical difficulty if, with Weismann, we
suppose the germ-plasm to be different in kind from the general
soma-plasm, and its least theoretical difficulty if, with Hertwig, we
suppose the essential matter of the reproductive cells to be similar in
kind to the essential substance of the general body cells. But, apart
from the differences between such theories, it supposes, in all cases
where an embryological development lies between parent and descendant,
the existence of a factor towards which our present knowledge of the
actual processes gives us no assistance. The separated hereditary mass
does not contain the organs of the adult; the Lamarckian factor would
involve the translation of the characters of the adult back into the
characters of the germ-cell in such a fashion that when the germ-cell
developed these characters would be re-translated again into those which
originally had been produced by co-operation between germ-plasm
characters and epigenetic factors. In the present state of our knowledge
the theoretical difficulty is not fatal to the Lamarckian supposition;
it does no more than demand a much more careful scrutiny of the supposed
cases. Such a scrutiny has been going on since Weismann first raised the
difficulty, and the present result is that no known case has appeared
which cannot be explained without the Lamarckian factor, and the vast
majority of cases have been resolved without any difficulty into the
ordinary events of which we have full experience. Taking the empirical
data in detail, it would appear first that the effects of single
mutilations are not inherited. The effects of long-continued mutilations
are not inherited, but Darwin cites as a possible case the Mahommedans
of Celebes, in whom the prepuce is very small. C. E. Brown-Sequard
thought that he had shown in the case of guinea-pigs the inheritance of
the results of nervous lesions, but analyses of his results leave the
question extremely doubtful. The inheritance of the effects of use and
disuse is not proved. The inheritance of the effects of changed
conditions of life is quite uncertain. Nageli grew Alpine plants at
Munich, but found that the change was produced at once and was not
increased in a period of thirteen years. Alphonse de Candolle starved
plants, with the result of producing better blooms, and found that
seedlings from these were also above the average in luxuriance of
blossom, but in these experiments the effects of selection during the
starvation, and of direct effect on the nutrition of the seeds, were not
eliminated. Such results are typical of the vast number of experiments
and observations recorded. The empirical issue is doubtful, with a
considerable balance against the supposed inheritance of acquired
characters.
_Empirical Study of Effects of Amphimixis._--Inheritance is
theoretically possible from each parent and from the ancestry of each.
In considering the total effect it is becoming customary to distinguish
between "blended" inheritance, where the offspring appears in respect of
any character to be intermediate between the conditions in the parents;
"prepotent" inheritance, where one parent is supposed to be more
effective than the other in stamping the offspring (thus, for instance,
Negroes, Jews and Chinese are stated to be prepotent in crosses);
"exclusive" inheritance, where the character of the offspring is
definitely that of one of the parents. Such a classification depends on
the interpretation of the word character, and rests on no certain
grounds. An apparently blended character or a prepotent character may on
analysis turn out to be due to the inheritance of a certain proportion
of minuter characters derived exclusively from either parent. H. de
Vries and later on a number of other biologists have advanced the
knowledge of heredity in crosses by carrying out further the
experimental and theoretical work of Gregor Mendel (see MENDELISM and
HYBRIDISM), and results of great practical importance to breeders have
already been obtained. These experiments and results, however, appear to
relate exclusively to sexual reproduction and almost entirely to the
crossing of artificial varieties of animals and plants. So far as they
go, they point strongly to the occurrence of alternate inheritance
instead of blended inheritance in the case of artificial varieties. On
the other hand, in the case of natural varieties it appears that blended
inheritance predominates. The difficulty of the interpretation of the
word "character" still remains and the Mendelian interpretation cannot
be dismissed with regard to the behaviour of any "character" in
inheritance until it is certain that it is a unit and not a composite.
There is another fundamental difficulty in making empirical comparisons
between the characters of parents and offspring. At first sight it seems
as if this mode of work were sufficiently direct and simple, and
involved no more than a mere collection of sufficient data. The cranial
index, or the height of a human being and of so many of his ancestors
being given, it would seem easy to draw an inference as to whether or no
in these cases brachycephaly or stature were inherited. But our modern
conceptions of the individual and the race make it plain that the
problems are not so simple. With regard to any character, the race type
is not a particular measurement, but a curve of variations derived from
statistics, and any individual with regard to the particular character
may be referable to any point of the curve. A tall race like the modern
Scots may contain individuals of any height within the human limits; a
dolichocephalic race like the modern Spaniards may contain extremely
round-headed individuals. What is meant by saying that one race is tall
or the other dolichocephalic, is merely that if a sufficiently large
number be chosen at random, the average height of the one race will be
great, the cranial index of the other low. It follows that the study of
variation must be associated with, or rather must precede, the empirical
study of heredity, and we are beginning to know enough now to be certain
that in both cases the results to be obtained are practically useless
for the individual case, and of value only when large masses of
statistics are collected. No doubt, when general conclusions have been
established, they must be acted on for individual cases, but the results
can be predicted not for the individual case, but only for the average
of a mass of individual cases. It is impossible within the limits of
this article to discuss the mathematical conceptions involved in the
formation and applications of the method, but it is necessary to insist
on the fact that these form an indispensable part of any valuable study
of empirical data. One interesting conclusion, which may be called the
"ancestral law" of heredity, with regard to any character, such as
height, which appears to be a blend of the male and female characters,
whether or no the apparent blend is really due to an exclusive
inheritance of separate components, may be given from the work of F.
Galton and K. Pearson. Each parent, on the average, contributes 1/4 or
(0.5)^2, each grandparent 1/16 or (0.5)^4, and each ancestor of n^th
place (0.5)^(2n). But this, like all other deductions, is applicable
only to the mass of cases and not to any individual case.
_Regression._--An important result of quantitative work brings into
prominence the steady tendency to maintain the type which appears to be
one of the most important results of amphimixis. In the tenth generation
a man has 1024 tenth grandparents, and is thus the product of an
enormous population, the mean of which can hardly differ from that of
the general population. Hence this heavy weight of mediocrity produces
regression or progression to type. Thus in the case of height, a large
number of cases being examined, it was found that fathers of a stature
of 72 in. had sons with a mean stature of 70.8 in., a regression towards
the normal stature of the race. Fathers with a stature of 66 in. had
sons with a mean of 68.3 in., a progression towards the normal. It
follows from this that where there is much in-and-in breeding the weight
of mediocrity will be less, and the peculiarities of the breed will be
accentuated.
_Atavism._--Under this name a large number of ordinary cases of
variation are included. A tall man with very short parents would
probably be set down as a case of atavism if the existence of a very
tall ancestor were known. He would, however, simply be a case of normal
variation, the probability of which may be calculated from a table of
stature variations in his race. Less marked cases set down to atavism
may be instances merely of normal regression. Many cases of more
abnormal structure, which are really due to abnormal embryonic or
post-embryonic development, are set down to atavism, as, for instance,
the cervical fistulae, which have been regarded as atavistic
persistences of the gill clefts. It is also used to imply the reversion
that takes place when domestic varieties are set free and when species
or varieties are crossed (see HYBRIDISM). Atavism is, in fact, a
misleading name covering a number of very different phenomena.
_Telegony_ is the name given to the supposed fact that offspring of a
mother to one sire may inherit characters from a sire with which the
mother had previously bred. Although breeders of stock have a strong
belief in the existence of this, there are no certain facts to support
it, the supposed cases being more readily explained as individual
variations of the kind generally referred to as "atavism." None the
less, two theoretical explanations have been suggested: (1) that
spermatozoa, or portions of spermatozoa, from the first sire may
occasionally survive within the mother for an abnormally long period;
(2) that the body, or the reproductive cells of the mother, may be
influenced by the growth of the embryo within her, so that she acquires
something of the character of the sire. The first supposition has no
direct evidence to support it, and is made highly improbable from the
fact that a second impregnation is always necessary. Against the second
supposition Pearson brings the cogent empirical evidence that the
younger children of the same sire show no increased tendency to resemble
him. (See TELEGONY.)
AUTHORITIES.--The following books contain a fair proportion of the new
and old knowledge on this subject:--W. Bateson, _Materials for the
Study of Variation_ (1894); Y. Delage, _La Structure du protoplasma et
les theories sur l'heredite_ (a very full discussion and list of
literature); G. H. T. Eimer, _Organic Evolution_, Eng. trans. by
Cunningham (1890); J. C. Ewart, _The Penycuik Experiments_ (1899); F.
Galton, _Natural Inheritance_ (1887); O. Hertwig, _Evolution or
Epigenesis?_ Eng. trans. by P. C. Mitchell (1896); K. Pearson, _The
Grammar of Science_ (1900); Verworn, _General Physiology_, Eng. trans.
(1899); A. Weismann, _The Germ Plasm_, Eng. trans. by Parker (1893).
Lists of separate papers are given in the annual volumes of the
_Zoological Record_ under heading "General Subject." (P. C. M.)
HEREFORD, a city and municipal and parliamentary borough, and the county
town of Herefordshire, England, on the river Wye, 144 m. W.N.W. of
London, on the Worcester-Cardiff line of the Great Western railway and
on the west-and-north joint line of that company and the North-Western.
It is connected with Ross and Gloucester by a branch of the Great
Western, and is the terminus of a line from the west worked by the
Midland and Neath & Brecon companies. Pop. (1901) 21,382. It is mainly
on the left bank of the river, which here traverses a broad valley, well
wooded and pleasant. The cathedral of St Ethelbert exemplifies all
styles from Norman to Perpendicular. The see was detached from Lichfield
in 676, Putta being its first bishop; and the modern diocese covers most
of Herefordshire, a considerable part of Shropshire, and small portions
of Worcestershire, Staffordshire and Monmouthshire; extending also a
short distance across the Welsh border. The removal of murdered
Aethelbert's body from Marden to Hereford led to the foundation of a
superior church, reconstructed by Bishop Athelstane, and burnt by the
Welsh in 1055. Begun again in 1079 by Bishop Robert Losinga, it was
carried on by Bishop Reynelm and completed in 1148 by Bishop R. de
Betun. In 1786 the great western tower fell and carried with it the west
front and the first bay of the nave, when the church suffered much from
unhappy restoration by James Wyatt, but his errors were partly corrected
by the further work of Lewis Cottingham and Sir Gilbert Scott in 1841
and 1863 respectively, while the present west front is a reconstruction
completed in 1905. The total length of the cathedral outside is 342 ft.,
inside 327 ft. 5 in., the nave being 158 ft. 6 in., the choir from
screen to reredos 75 ft. 6 in. and the lady chapel 93 ft. 5 in. Without,
the principal features are the central tower, of Decorated work with
ball-flower ornament, formerly surmounted by a timber spire; and the
north porch, rich Perpendicular with parvise. The lady chapel has a bold
east end with five narrow lancet windows. The bishop's cloisters, of
which only two walks remain, are Perpendicular of curious design, with
heavy tracery in the bays. A picturesque tower at the south-east corner,
in the same style, is called the "Lady Arbour," but the origin of the
name is unknown. Of the former fine decagonal Decorated chapter-house,
only the doorway and slight traces remain. Within, the nave has Norman
arcades, showing the wealth of ornament common to the work of this
period in the church. Wyatt shortened it by one bay, and the clerestory
is his work. There is a fine late Norman font, springing from a base
with the rare design of four lions at the corners. The south transept is
also Norman, but largely altered by the introduction of Perpendicular
work. The north transept was wholly rebuilt in 1287 to contain the
shrine of St Thomas de Cantilupe, bishop of Hereford, of which there
remains the magnificent marble pedestal surmounted by an ornate arcade.
The fine lantern, with its many shafts and vaulting, was thrown open to
the floor of the bell-chamber by Cottingham. The choir screen is a
florid design by Sir Gilbert Scott, in light wrought iron, with a wealth
of ornament in copper, brass, mosaic and polished stones. The dark choir
is Norman in the arcades and the stage above, with Early English
clerestory and vaulting. At the east end is a fine Norman arch, blocked
until 1841 by a Grecian screen erected in 1717. The choir stalls are
largely Decorated. The organ contains original work by the famous
builder Renatus Harris, and was the gift of Charles II. to the
cathedral. The small north-east and south-east transepts are Decorated
but retain traces of the Norman apsidal terminations eastward. The
eastern lady chapel, dated about 1220, shows elaborate Early English
work. On the south side opens the little Perpendicular chantry of Bishop
Audley (1492-1502). In the north choir aisle is the beautiful
fan-vaulted chantry of Bishop Stanbury (1470). The crypt is remarkable
as being, like the lady chapel, Early English, and is thus the only
cathedral crypt in England of a later date than the 11th century. The
ancient monastic library remains in the archive room, with its heavy oak
cupboards. Deeds, documents and several rare manuscripts and relics are
preserved, and several of the precious books are still secured by
chains. But the most celebrated relic is in the south choir aisle. This
is the Map of the World, dating from about 1314, the work of a
Lincolnshire monk, Richard of Haldingham. It represents the world as
surrounded by ocean, and embodies many ideas taken from Herodotus, Pliny
and other writers, being filled with grotesque figures of men, beasts,
birds and fishes, together with representations of famous cities and
scenes of scriptural classical story, such as the Labyrinth of Crete,
the Egyptian pyramids, Mount Sinai and the journeyings of the
Israelites. The map is surmounted by representations of Paradise and the
Day of Judgment.
From the south-east transept of the cathedral a cloister leads to the
quadrangular college of the Vicars-Choral, a beautiful Perpendicular
building. On this side of the cathedral, too, the bishop's palace,
originally a Norman hall, overlooks the Wye, and near it lies the castle
green, the site of the historic castle, which is utterly effaced. There
is here a column (1809) commemorating the victories of Nelson. The
church of All Saints is Early English and Decorated, and has a lofty
spire. Both this and St Peter's (originally Norman) have good carved
stalls, but the fabric of both churches is greatly restored. One only of
the six gates and a few fragments of the old walls are still to be seen,
but there are ruins of the Black Friars' Monastery in Widemarsh, and a
mile out of Hereford on the Brecon Road, the White Cross, erected in
1347 by Bishop Louis Charlton, and restored by Archdeacon Lord Saye and
Sele, commemorates the departure of the Black Plague. Of domestic
buildings the "Old House" is a good example of the picturesque
half-timbered style, dating from 1621, and the Coningsby Hospital
(almshouses) date from 1614. The inmates wear a remarkable uniform of
red, designed by the founder, Sir T. Coningsby. St Ethelbert's hospital
is an Early English foundation. Old-established schools are the
Cathedral school (1384) and the Blue Coat school (1710); there is also
the County College (1880). The public buildings are the shire hall in St
Peter's Street, in the Grecian Doric style, with a statue in front of it
of Sir George Cornewall Lewis, who represented the county in parliament
from 1847 to 1852, the town hall (1904), the corn-exchange (1858), the
free library and museum in Broad Street; the guildhall and mansion
house. A musical festival of the choirs of Hereford, Gloucester and
Worcester cathedrals is held annually in rotation at these cities.
The government is in the hands of a municipal council consisting of a
mayor, 6 aldermen and 18 councillors. Area, 5031 acres.