THE LAW OF VARIATION.
We come now to consider another law, by which that of similarity is
greatly modified, to wit, the law of variation or divergence. All
organic beings, whether plants or animals, possess a certain
flexibility or pliancy of organization, rendering them capable of
change to a greater or less extent. When in a state of nature
variations are comparatively slow and infrequent, but when in a state
of domestication they occur much oftener and to a much greater extent.
The greater variability in the latter case is doubtless owing, in some
measure, to our domestic productions being reared under conditions of
life not so uniform, and different from, those to which the parent
species was exposed in a state of nature.
Flexibility of organization in connexion with climate, is seen in a
remarkable degree in Indian corn. The small Canada variety, growing
only three feet high and ripening in seventy to ninety days when
carried southward, gradually enlarges in the whole plant until it may
be grown twelve feet high and upwards, and requires one hundred and
fifty days to ripen its seed. A southern variety brought northward,
gradually dwindles in size and ripens earlier until it reaches a type
specially fitted to its latitude.
Variation, although the same in kind, is greater in degree, among
domesticated plants than among animals. From the single wild variety
of the potato as first discovered and taken to Europe, have sprung
innumerable sorts. Kemp, in his work on Agricultural Physiology, tells
us, that on the maritime cliffs of England, there exists a little
plant with a fusiform root, smooth glaucous leaves, flowers similar to
wild mustard and of a saline taste. It is called by botanists,
_Brassica oleracea_. By cultivation there have been obtained from this
insignificant and apparently useless plant--
1st, all borecoles or kails, 12 varieties or more.
2d, all cabbages having heart.
3d, the various kinds of Savoy cabbages.
4th, Brussels sprouts.
5th, all the broccolis and cauliflowers which do not heart.
6th, the rape plant.
7th, the ruta baga or Swedish turnip.
8th, yellow and white turnips.
9th, hybrid turnips.
10th, kohl rabbi.
Similar examples are numerous among our common useful plants, and
among flowers the dahlia and verbena furnish an illustration of
countless varieties, embracing numberless hues and combinations of
color, from purest white through nearly all the tints of the rainbow
to almost black, of divers hights too, and habits of growth, springing
up under the hand of cultivation in a few years from plants which at
first yielded only a comparatively unattractive and self-colored
flower. In brief, it may be said, that nearly or quite all the
choicest productions both of our kitchen and flower gardens are due to
variations induced by cultivation in a course of years from plants
which in their natural condition would scarcely attract a passing
glance.
We cannot say what might have been the original type of many of our
domestic animals, for the inquiry would carry us beyond any record of
history or tradition regarding it, but few doubt that all our
varieties of the horse, the ox, the sheep and the dog, sprang each
originally from a single type, and that the countless variations are
due to causes connected with their domestication. Of those reclaimed
within the period of memory may be named the turkey. This was unknown
to the inhabitants of the old continent until discovered here in a
wild state. Since then, having been domesticated and widely
disseminated, it now offers varieties of wide departure from the
original type, and which have been nurtured into self-sustaining
breeds, distinguished from each other by the possession of peculiar
characteristics.
Among what are usually reckoned the more active causes of variation
may be named climate, food and habit.
Animals in cold climates are provided with a thicker covering of hair
than in warmer ones. Indeed, it is said that in some of the tropical
provinces of South America, there are cattle which have an extremely
rare and fine fur in place of the ordinary pile of hair. Various other
instances could be cited, if necessary, going to show that a
beneficent Creator has implanted in many animals, to a certain extent,
a _power of accommodation_ to the circumstances and conditions amid
which they are reared.
The _supply of food_, whether abundant or scanty, is one of the most
active cases of variation known to be within the control of man. For
illustration of its effect, let us suppose two pairs of twin calves,
as nearly alike as possible, and let a male and a female from each
pair be suckled by their mothers until they wean themselves, and be
fed always after with plenty of the most nourishing food; and the
others to be fed with skimmed milk, hay tea and gruel at first, to be
put to grass at two months old, and subsequently fed on coarse and
innutritious fodder. Let these be bred from separately, and the same
style of treatment kept up, and not many generations would elapse
before we had distinct varieties, or breeds, differing materially in
size, temperament and time of coming to maturity.
Suppose other similar pairs, and one from each to be placed in the
richest blue-grass pastures of Kentucky, or in the fertile valley of
the Tees; always supplied with abundance of rich food, these live
luxuriously, grow rapidly, increase in hight, bulk, thickness, every
way, they early reach the full size which they are capable of
attaining; having nothing to induce exertion, they become inactive,
lazy, lethargic and fat. Being bred from, the progeny resemble the
parents, "only more so." Each generation acquiring more firmly and
fixedly the characteristics induced by their situation, these become
hereditary, and we by and by have a _breed_ exhibiting somewhat of the
traits of the Teeswater or Durhams from which the improved Short-horns
of the present day have been reared.
The others we will suppose to have been placed on the hill-sides of
New England, or on the barren Isle of Jersey, or on the highlands of
Scotland, or in the pastures of Devonshire. These being obliged to
roam longer for a scantier repast grow more slowly, develop their
capabilities in regard to size not only more slowly, but, perhaps, not
fully at all--they become more active in temperament and habit,
thinner and flatter in muscle. Their young cannot so soon shift for
themselves and require more milk, and the dams yield it. Each
generation in its turn becomes more completely and fully adapted to
the circumstances amid which they are reared, and if bred
indiscriminately with any thing and every thing else, we by and by
have the common mixed cattle of New England, miscalled natives; or if
kept more distinct, we have something approaching the Devon, the
Ayrshire, or the Jersey breeds.
A due consideration of the natural effect of climate and food is a
point worthy the special attention of the stock-husbandman. If the
breeds employed be well adapted to the situation, and the capacity of
the soil is such as to feed them fully, profit may be safely
calculated upon. Animals are to be looked upon as machines for
converting herbage into money. Now it costs a certain amount to keep
up the motive power of any machine, and also to make good the wear and
tear incident to its working; and in the case of animals it is only so
much as is digested and assimilated, _in addition to the amount thus
required_, which is converted into meat, milk or wool; so that the
greater the proportion which the latter bears to the former, the
greater will be the _profit_ to be realized from keeping them.
There has been in New England generally a tendency to choose animals
of large size, as large as can be had from any where, and if they
possess symmetry and all other good qualities commensurate with the
size, and if plenty of nutritious food can be supplied, there is an
advantage gained by keeping such, for it costs less, other things
being equal, to shelter and care for one animal than for two. But our
pastures and meadows are not the richest to be found any where, and if
we select such as require, in order to give the profit which they are
capable of yielding, more or richer food than our farms can supply, or
than we have the means to purchase, we must necessarily fail to reap
as much profit as we might by the selection of such as could be easily
fed upon home resources to the point of highest profit.
Whether the selection be of such as are either larger or smaller than
suit our situation, they will, and equally in both cases, vary by
degrees towards the fitting size or type for the locality in which
they are kept, but there is this noteworthy difference, that if larger
ones be brought in, they will not only diminish, but deteriorate,
while if smaller be brought in, they will enlarge _and improve_.
The bestowal of food sufficient both in amount and quality to enable
animals to develop all the excellencies inherent in them, and to
obtain all the profit to be derived from them, is something very
distinct from undue forcing or pampering. This process may produce
wonderful animals to look at, but neither useful nor profitable ones,
and there is danger of thus producing a most undesirable variation,
for, as in plants, we find that forcing, pampering, high culture or
whatever else it may be called, may be carried so far as to result in
the production of double flowers, (an unnatural development,) and
these accompanied with greater or less inability to perfect seed, so
in animals, the same process may be carried far enough to produce
sterility. Instances are not wanting, and particularly among the more
recent improved Short-horns, of impotency among the males and of
barrenness in the females, and in some cases where they have borne
calves they have failed to secrete milk for their nourishment.[3]
Impotency in bulls of various breeds has not unfrequently occurred
from too high feeding, and especially if connected _with lack of
sufficient exercise_.[4]
_Habit_ has a decided influence towards inducing variation. As the
blacksmith's right arm becomes more muscular from the habit of
exercise induced by his vocation, so we find in domestic animals that
use, or the demand created by habit, is met by a development or change
in the organization adapted to the requirement. For instance, with
cows in a state of nature or where required only to suckle their
young, the supply of milk is barely fitted to the requirement. If more
is desired, and if the milk be drawn completely and regularly, the
yield is increased and continued longer. By keeping up the demand
there is induced in the next generation a greater development of the
secreting organs, and more milk is given. By continuing the practice,
by furnishing the needful conditions of suitable food, &c., and by
selecting in each generation those animals showing the greatest
tendency towards milk, a breed specially adapted for the dairy may be
established. It is just by this mode that the Ayrshires have, in the
past eighty or a hundred years, been brought to be what they are, a
breed giving more good milk upon a given quantity of food than any
other.
It is because the English breeders of modern Short-horns altogether
prefer beef-making to milk-giving properties that they have
constantly fostered variation in favor of the one at the expense of
the other until the milking quality in many families is nearly bred
out. It was not so formerly--thirty years ago the Short-horns (or as
they were then usually called, the Durhams) were not deficient in
dairy qualities, and some families were famous for large yield. By
properly directed efforts they might, doubtless, be bred back to milk,
but of this there is no probability, at least in England, for the
tendency of modern practice is very strong toward having each breed
specially fitted to its use--the dairy breeds for milk and the beef
breeds for meat only. The requirements of the English breeder are in
some respects quite unlike those of New England farmers--for instance,
as they employ no oxen for labor there is no inducement to cultivate
working qualities even, in connection with beef.
As an illustration of the effect of habit, Darwin[5] cites the
domestic duck, of which he says, "I find that the bones of the wing
weigh less, and the bones of the leg more, in proportion to the whole
skeleton, than do the same bones in the wild duck; and I presume that
this change may be safely attributed to the domestic duck flying much
less and walking more than its wild parent." And again, "not a single
domestic animal can be named which has not in some country drooping
ears, and the view suggested by some authors, that the drooping is due
to the disuse of the muscles of the ear, from the animals not being
much alarmed by danger, seems probable."
Climate, food and habit are the principal causes of variation which
are known to be in any marked degree under the control of man; and the
effect of these is, doubtless, in some measure indirect and
subservient to other laws, of reproduction, growth and inheritance, of
which we have at present very imperfect knowledge. This is shown by
the fact that the young of the same litter sometimes differ
considerably from each other, though both the young and their parents
have apparently been exposed to exactly the same conditions of life;
for had the action of these conditions been specific or direct and
independent of other laws, if any of the young had varied, the whole
would probably have varied in the same manner.
Numberless hypotheses have been started to account for variation. Some
hold that it is as much the function of the reproductive system to
produce individual differences as it is to make the child like the
parents. Darwin says "the reproductive system is eminently susceptible
to changes in the conditions of life; and to this system being
functionally disturbed in the parents I chiefly attribute the varying
or plastic condition of the offspring. The male and female sexual
elements seem to be affected before that union takes place which is to
form a new being. But why, because the re-productive system is
disturbed this or that part should vary more or less, we are
profoundly ignorant. Nevertheless we can here and there dimly catch a
faint ray of light, and we may feel sure that there must be some cause
for each deviation of structure however slight."
It may be useless for us to speculate here upon the laws which govern
variations. The fact that these exist is what the breeder has to deal
with, and a most important one it is, for it is this chiefly, which
makes hereditary transmission the problem which it is. His aim should
ever be _to grasp and render permanent and increase so far as
practicable, every variation for the better, and to reject for
breeding purposes such as show a downward tendency_.
That this may be done, there is abundant proof in the success which
has in many instances attended the well directed efforts of
intelligent breeders. A remarkable instance is furnished in the new
Mauchamp-Merino sheep of Mons. Graux, which originated in a single
animal, a product of the law of variation, and which by skillful
breeding and selection has become an established breed of a peculiar
type and possessing valuable properties. Samples of the wool of these
sheep were shown at the great exhibition in London, in 1851, and
attracted much attention. It was also shown at the great recent
Agricultural Exhibition at Paris. A correspondent of the _Mark Lane
Express_, says:
"One of the most interesting portions of the sheep-show is that
of the Mauchamp variety of Merinos, having a new kind of wool,
glossy and silky, similar to mohair. This is an instance of an
entirely new breed being as it were created from a mere sport of
nature. It was originated by Mons. J.L. Graux. In the year 1828,
a Merino ewe produced a peculiar ram lamb, having a different
shape from the usual Merino, and possessing a long, straight,
and silky character of wool. In 1830, M. Graux obtained by this
ram one ram and one ewe, having the silky character of wool. In
1831, among the produce were four rams and one ewe with similar
fleeces; and in 1833 there were rams enough of the new sort to
serve the whole flock of ewes. In each subsequent year the lambs
were of two kinds; one possessing the curled elastic wool of the
old Merinos, only a little longer and finer; the other like the
new breed. At last, the skillful breeder obtained a flock
combining the fine silky fleece with a smaller head, broader
flanks, and more capacious chest; and several flocks being
crossed with the Mauchamp variety, have produced also the
Mauchamp-Merino breed. The pure Mauchamp wool is remarkable for
its qualities as a combing-wool, owing to the strength, as well
as the length and fineness of the fibre. It is found of great
value by the manufacturers of Cashmere shawls and similar
goods, being second only to the true Cashmere fleece, in the
fine flexible delicacy of the fibre; and when in combination
with Cashmere wool, imparting strength and consistency. The
quantity of the wool has now become as great or greater than
from ordinary Merinos, while the quality commands for it
twenty-five per cent. higher price in the French market. Surely
breeders cannot watch too closely any accidental peculiarity of
conformation or characteristic in their flocks or herds."
Mons. Vilmorin, the eminent horticulturist of Paris, has likened the
law of similarity to the centripetal force, and the law of variation
to the centrifugal force; and in truth their operations seem
analogous, and possibly they may be the same in kind, though certainly
unlike in this, that they are not reducible to arithmetical
calculation and cannot be subjected to definite measurement. His
thought is at least a highly suggestive one and may be pursued with
profit.
Among the "faint rays" alluded to by Mr. Darwin as throwing light upon
the changes dependent on the laws of reproduction, there is one,
perhaps the brightest yet seen, which deserves our notice. It is the
apparent influence of the male first having fruitful intercourse with
a female upon her subsequent offspring by other males. Attention was
first directed to this by the following circumstance, related by Sir
Everard Home: A young chestnut mare, seven-eighths Arabian, belonging
to the Earl of Morton, was covered in 1815 by a Quagga, which is a
species of wild ass from Africa, and marked somewhat in the style of a
Zebra. The mare was covered but once by the Quagga, and after a
pregnancy of eleven months and four days gave birth to a hybrid, which
had, as was expected, distinct marks of the Quagga, in the shape of
its head, black bars on the legs and shoulders, &c. In 1817, 1818 and
1821, the same mare was covered by a very fine black Arabian horse,
and produced successively three foals, and although she had not seen
the Quagga since 1816, they all bore his curious and unequivocal
markings.
Since the occurrence of this case numerous others of a similar
character have been observed, a few of which may be mentioned. Mr.
McGillivray says, that in several foals in the royal stud at Hampton
Court, got by the horse "Actæon," there were unmistakable marks of the
horse "Colonel." The dams of these foals were bred from by Colonel the
previous year.
A colt, the property of the Earl of Suffield, got by "Laurel," so
resembled another horse, "Camel," that it was whispered and even
asserted at Newmarket that he must have been got by "Camel." It was
ascertained, however, that the mother of the colt bore a foal the
previous year by "Camel."
Alex. Morrison, Esq., of Bognie, had a fine Clydesdale mare which in
1843 was served by a Spanish ass and produced a mule. She afterwards
had a colt by a horse, which bore a very marked likeness to a
mule--seen at a distance, every one sets it down at once as a mule.
The ears are nine and one-half inches long,--the girth not quite six
feet, stands above sixteen hands high. The hoofs are so long and
narrow that there is a difficulty in shoeing them, and the tail is
thin and scanty. He is a beast of indomitable energy and durability,
and highly prized by his owner.
Numerous similar cases are on record,[6] and it appears to have been
known among the Arabs for centuries, that a mare which has first borne
a mule, is ever after unfit to breed pure horses;[7] and the fact
seems now to be perfectly well understood in all the mule-breeding
States of the Union.
A pure Aberdeenshire heifer, the property of a farmer in Forgue, was
served with a pure Teeswater bull to which she had a first cross calf.
The following season the same cow was served with a pure Aberdeenshire
bull, the produce was in appearance a cross-bred calf, which at two
years old had long horns; the parents were both hornless.
A small flock of ewes, belonging to Dr. W. Wells in the island of
Grenada, were served by a ram procured for the purpose;--the ewes were
all white and woolly; the ram was quite different,--of a chocolate
color, and hairy like a goat. The progeny were of course crosses but
bore a strong resemblance to the male parent. The next season, Dr.
Wells obtained a ram of precisely the same breed as the ewes, but the
progeny showed distinct marks of resemblance to the former ram, in
color and covering. The same thing occurred on neighboring estates
under like circumstances.
Six very superior pure-bred black-faced horned ewes, belonging to Mr.
H. Shaw of Leochel-Cushnie, were served by a Leicester ram,
(white-faced and hornless.) The lambs were crosses. The next year they
were served by a ram of exactly the same breed as the ewes themselves.
To Mr. Shaw's astonishment the lambs were without an exception
hornless and brownish in the face, instead of being black and horned.
The third year (1846) they were again served by a superior ram of
their own breed, and again the lambs were mongrels, but showed less of
the Leicester characteristics than before. Mr. Shaw at last parted
from these fine ewes without obtaining a single pure-bred lamb.[8]
"It has been noticed that a well bred bitch, if she have been
impregnated by a mongrel dog, will not although lined subsequently by
a pure dog, bear thorough-bred puppies in the next two or three
litters."[9]
The like occurrence has been noticed in respect of the sow. "A sow of
the black and white breed became pregnant by a boar of the wild breed
of a deep chestnut color. The pigs produced were duly mixed, the color
of the boar being in some very predominant. The sow being afterwards
put to a boar of the same breed as herself, some of the produce were
still stained or marked with the chestnut color which prevailed in the
first litter and the same occurred after a third impregnation, the
boar being then of the same kind as herself. What adds to the force of
this case is that in the course of many years' observation the breed
in question was never known to produce progeny having the slightest
tinge of chestnut color."[10]
The above are a few of the many instances on record tending to show
the influence of a first impregnation upon subsequent progeny by other
males. Not a few might also be given showing that the same rule holds
in the human species, of which a single one will suffice here:--"A
young woman residing in Edinburgh, and born of white parents, but
whose mother previous to her marriage bore a mulatto child by a negro
man servant, exhibits distinct traces of the negro. Dr. Simpson, whose
patient at one time, the young woman was, recollects being struck with
the resemblance, and noticed particularly that the hair had the
qualities characteristic of the negro."
Dr. Carpenter, in the last edition of his work on physiology, says it
is by no means an infrequent occurrence for a widow who has married
again to bear children resembling her first husband.
Various explanations have been offered to account for the facts
observed, among which the theory of Mr. McGillivray, V.S., which is
endorsed by Dr. Harvey, and considered (as we shall presently see) as
very probable at least by Dr. Carpenter, seems the most satisfactory.
Dr. Harvey says:
"Instances are sufficiently common among the lower animals where
the offspring exhibit more or less distinctly over and beyond
the characters of the male by which they were begotten, the
peculiarities also of a male by which their mother at some
former period had been impregnated. * * * Great difficulty has
been felt by physiological writers in regard to the proper
explanation of this kind of phenomena. They have been ascribed
by some to a permanent impression made somehow by the semen of
the first male on the genitals and more particularly on the ova
of the female:[11] and by others to an abiding influence exerted
by him on the imagination and operating at the time of her
connection subsequently with other males and perhaps during her
pregnancy; but they seem to be regarded by most physiologists as
inexplicable.
Very recently, in a paper published in the Aberdeen Journal, a
Veterinary Surgeon, Mr. James McGillivray of Huntley, has
offered an explanation which seems to me to be the true one. His
theory is that "_when a pure animal of any breed has been
pregnant to an animal of a different breed, such pregnant animal
is a cross ever after, the purity of her blood being lost in
consequence of her connection with the foreign animal, herself_
BECOMING A CROSS FOREVER, _incapable of producing a pure calf of
any breed_."
Dr. Harvey believes "that while as all allow, a portion of the
mother's blood is continually passing by absorption and assimilation
into the body of the foetus, in order to its nutrition and
development, a portion of the blood of the foetus is as constantly
passing in like manner into the body of the mother; that as this
commingles there with the general mass of the mother's own blood, it
inoculates her system with the constitutional qualities of the foetus,
and that, as these qualities are in part derived to the foetus from
the male progenitor, the peculiarities of the latter are thereby so
ingrafted on the system of the female as to be communicable by her to
any offspring she may subsequently have by other males."
In support of this view, Mr. McGillivray cites a case in which there
was presented unmistakable evidence that the organization of the
placenta admits the return of the venous blood to the mother; and Dr.
Harvey, with much force, suggests that the effect produced is
analogous to the known fact that constitutional syphilis has been
communicated to a female who never had any of the primary symptoms.
Regarding the occurrence of such phenomena, Dr. Harvey under a later
date says: "since then I have learned that many among the agricultural
body in this district are familiar to a degree that is annoying to
them with the facts then adduced in illustration of it, finding that
after breeding crosses, their cows though served with bulls of their
own breed yield crosses still or rather mongrels; that they were
already impressed with the idea of contamination of blood as the cause
of the phenomenon; that the doctrine so intuitively commended itself
to their minds as soon as stated, that they fancied they were told
nothing but what they knew before, so just is the observation that
truth proposed is much more easily perceived than without such
proposal is it discovered."[12]
Dr. Carpenter, speaking of phenomena analogous to what are here
alluded to, says:
"Some of these cases appear referable to the strong impression left by
the first male parent upon the female; but there are others which seem
to render it more likely that the blood of the female has imbibed from
that of the foetus, through the placental circulation, some of the
attributes which the latter has derived from its male parent, and that
the female may communicate these, with those proper to herself, to the
subsequent offspring of a different male parentage. This idea is borne
out by a great number of important facts. * * As this is a point of
great practical importance it may be hoped that those who have the
opportunity of bringing observation to bear upon it, will not omit to
do so."
In the absence of more general and accurate observations directed to
this point, it is impossible to say to what extent the first male
produces impression upon subsequent progeny by other males. There can
be no doubt, however, but that such an impression is made. The
instances where it is of so marked and obvious a character as in some
of those just related may be comparatively few, yet there is abundant
reason to believe, that although in a majority of cases the effect may
be less noticeable, it is not less real, and demands the special
attention of all breeders.
Whether this result is to be ascribed to inoculation of the system of
the female with the characteristics of the male through the foetus, or
to any other mode of operation, it is obviously of great advantage for
every breeder to know it and thereby both avoid error and loss and
secure profit. It is a matter which deserves thorough investigation
and the observations should be minute and have regard not only to
peculiarities of form, but also to qualities and characteristics not
so obvious; for instance there may be greater or less hardiness,
endurance or aptitude to fatten. These may be usually more dependent
on the dam, but the male is never without a degree of influence upon
them, and it is well established that aptitude to fatten is usually
communicated by the Short-horn bull to crosses with cattle of mixed or
mongrel origin which are often very deficient in this desirable
property.
Mr. McGillivray says: "A knowledge of the fact must be of the greatest
benefit to the breeder in two ways, positively and negatively. I have
known very great disappointment and loss result from allowing an
inferior male to serve a first rate female--the usefulness of such
female being thereby forever destroyed. As for the positive benefits
arising from the inoculation--they are obvious to any unbiased mind.
The black polled and Aberdeenshire cattle common to this country
(Scotland) may be, and often are, improved by the following plan:
Select a good, well formed, and healthy heifer--put her, in proper
season, to a pure Short-horn bull; after the calf to this Durham bull,
breed from the cow with bulls of her own breed; occasionally, and most
likely the first time, a red calf ultimately having horns will appear
even from the polled bull and cow; but in general the calves will be
of the same type with the polled parents but with many points
improved, and an aptitude to fatten, to come earlier to maturity, &c.,
such as no one of the pure polled or Aberdeenshire breed ever
exhibited in this country, or any other country, however well kept,
previous to the introduction of the Short-horn breed. The offspring of
these breeds thus improved, when bred from again, will exhibit many
points and qualities of excellence similar to the best crosses but
retaining much of the hardiness of the original stock, no mean
consideration for this changeable and often severe climate. And,
moreover, such crosses,--for they are crosses--will command high
prices as improved polled or Aberdeenshire cattle. I happen to know of
a case where a farmer, from a distance purchased a two year old
heifer of the stamp referred to, for the purpose of improving his
polled cattle, and for this heifer he paid fifty guineas."
The knowledge of this law[13] gives us a clue to the cause of many of
the disappointments of which practical breeders often complain and to
the cause of many variations otherwise unaccountable, and it suggests
particular caution as to the first male employed in the coupling of
animals, a matter which has often been deemed of little consequence in
regard to cattle, inasmuch as fewer heifers' first calves are reared,
than of such as are borne subsequently.
Another faint ray of light touching the causes of variation is
afforded us by the fact that the qualities of offspring are not only
dependent on the habitual conditions of the parents, but also upon any
peculiar condition existing at the time of sexual congress. For
instance, the offspring of parents ordinarily healthy and temperate,
but begotten in a fit of intoxication, would be likely to suffer
permanently, both physically and mentally, from the condition which
the parents had temporarily brought upon themselves. On the other
hand, offspring begotten of parents in an unusually healthy and active
condition of body and mind, would likely be unusually endowed both
mentally and physically. The Arabs in breeding horses take advantage
of this fact, for before intercourse, both sire and dam are actively
exercised, not to weariness, but sufficiently to induce the most
vigorous condition possible. Of this, too, we have proof in the
phenomenon sometimes observed by breeders, that a strong mental
impression made upon the female by a particular male, will give the
offspring a resemblance to him, even though she have no sexual
intercourse with him. Of this, Mr. Boswell in his prize essay
published in 1828, gives a remarkable instance. He says that Mr.
Mustard of Angus, one of the most intelligent breeders he had ever met
with, told him that one of his cows chanced to come into season while
pasturing on a field bounded by that of one of his neighbors, out of
which field an ox jumped and went with the cow until she was brought
home to the bull. The ox was white, with black spots, and horned. Mr.
Mustard had not a horned beast in his possession, nor one with any
white on it. Nevertheless, the produce of the following spring was a
black and white calf with horns.
The case of Jacob is often quoted in support of this view, and
although many believe some miraculous agency to have been exerted in
his case, and though he could say with truth, "God hath taken away the
cattle of your father and given them to me," it seems, on the whole,
more probable, inasmuch as supernatural agency may never be presumed,
except where we know, or have good reason to believe, that natural
causes are insufficient, that God "gave" them, as he now gives to
some, riches or honors; that is to say, by virtue of the operation of
natural laws. If all who keep cattle would exercise a tithe of the
patriarch's shrewdness and sagacity in improving their stock, we
should see fewer ill-favored kine than at present.
The possibility of some effect being produced by a strong impression
at the time of conception, is not to be confounded with the popular
error that "marks" upon an infant[14] are due to a transient, although
strong impression upon the imagination of the mother at any period of
gestation, which is unsupported by facts and absurd; but there are
facts sufficient upon record to prove that _habitual_ mental
condition, and especially at an early stage of pregnancy, _may_ have
the effect to produce some bodily deformity, and should induce great
caution.
FOOTNOTES:
[3] See Rowley's Prize Report on Farming in Derbyshire, in Journal of
Royal Agricultural Society, Vol. 14.
[4] A _working bull_, though perhaps not so pleasing to the eye as a
fat one, (for fat sometimes covers a multitude of defects,) is a surer
stock-getter; and his progeny is more likely to inherit full health and
vigor.
[5] In his Origin of Species.
[6] It was long ago stated by Haller, that when a mare had a foal by an
ass and afterwards another by a horse, the second offspring begotten by
the horse nevertheless approached in character to a mule.
[7] See Abd el Kader's letter.
[8] Journal of Medical Science, 1850.
[9] Kirke's Physiology.
[10] Philosophical Transactions for 1821.
[11] The late M.A. Cuming, V.S., of New Brunswick, once remarked to the
writer, that it might be due to the fact that the nerves of the uterus,
which before the first impregnation were in a rudimentary state, were
developed under a specific influence from the semen of the first male,
and that they might retain so much of a peculiar style of development
as to impress upon future progeny by other males the likeness of the
first.
[12] Edinburgh Journal Medical Science, 1849.
[13] A very striking fact may be related in this connection, which
while it may or may not have a practical bearing on the breeding of
domestic animals, shows forcibly how mysterious are some of the laws of
reproduction. It is stated by the celebrated traveler, Count de
Strzelecki, in his Physical Description of New South Wales and Van
Dieman's Land. "Whenever," he says, "a fruitful intercourse has taken
place between an aboriginal woman and an European male, that aboriginal
woman is forever after incapable of being impregnated by a male of her
own nation, although she may again be fertile with a European." The
Count, whose means and powers of observation are of the highest
possible order, affirms that "hundreds of instances of this
extraordinary fact are on record in the writer's memoranda all
recurring invariably under the same circumstances, all tending to prove
that the sterility of the female, which is relative only to one and not
to the other male is not accidental, but follows laws as cogent though
as mysterious as the rest of those connected with generation." The
Count's statement is endorsed by Dr. Maunsell of Dublin, Dr. Carmichael
of Edinburgh, and the late Prof. Goodsir, who say they have learned
from independent sources that as regards Australia, Strzelecki's
statement is unquestionable and must be regarded as the expression of a
law of nature. The law does not extend to the negro race, the fertility
of the negro female not being apparently impaired by previous fruitful
intercourse with a European male.
In reply to an inquiry made whether he had ever noticed exceptional
cases, the Count says: "It has not come under my cognizance to see or
hear of a native female which having a child with a European had
afterwards any offspring with a male of her own race."
The Count's statement is suggestive as to the disappearance of the
aborigines of some countries. This has often been the subject of severe
comment and is generally ascribed to the rum and diseases introduced by
the white man. It would now appear that other influences have also been
operative.
[14] Carpenter's Physiology, new edition, page 783.