PROGRESS OF ZOOLOGY. 
841 
duces like/* with as much discretion as Mr. Jonathan Webb, 
the modern master of the art of sheep breeding. Dr. Beke, 
who has just traversed the country where Jacob grew rich in 
tending Laban’s flocks, reports that “ ring-stroked, speckled, 
and grisled cattle,” abound there, and apparently within such 
a circumscribed range as to render it probable that the race 
has maintained its integrity since the day of the patriarch's 
servitude, which our marginal Bibles place at a date 3600 
years antecedent to the present time. The tailless cats of the 
Isle of Man, and the tailless poultry of Burmah, are scarcely 
to be traced back to their parentage, and have all the charac¬ 
teristics of true species as far as their constancy of reproduc¬ 
tion is concerned. In his twentieth chapter Livingstone says, 
(i Near Massangano I observed what seemed to be an effort 
of Nature to furnish a variety of domestic fowls capable of 
bearing with comfort the intense heat of the sun. Their 
feathers were curled upwards; thus giving shade to the body 
without increasing the heat. They are here named ‘kisafu* by 
the natives, and c arripiada', or shivering, by the Portuguese. 
There seems to be a tendency in Nature to afford varieties 
adapted to the convenience of man. For instance, a very 
short-legged species of fowl was obtained by the Boers, who 
required one that could be easily caught in their frequent 
removals. A similar instance of securing a variety occurred 
in the short-limbed sheep of America.” Such things as these 
are matters of daily observation; the question is, to what law 
are they subject, or, in other words, what is the philosophy 
of their occurrence? If Mr. Darwin had sent forth his book 
as a collection of data, instead of as the statement of an 
hypothesis, there would have been the same broad field for 
discussion, but with the advantage of greater freedom; for it 
is in vain to seek for the philosophy of varieties until we have 
arrived at an unexceptional theory of species, which we 
certainly have not, unless it be the vague definition that a 
species is a congenital expression of all the forces concerned 
in its production. Our conclusions, for the present, are pro¬ 
visional, and each new conclusion arrived at simply pushes 
the inquiry a stage farther back. The subject is as much 
one for experiment as for inquiry into the accidents of nature. 
The intermediate form between the horse and the ass is a 
mule, which is infertile with another mule of the opposite 
sex, and it is thenceforth concluded that all hybrids of a given 
class are incapable of procreation among themselves. But 
M. Rouy, of Angouleme, is reported to breed hybrids between 
the hare and the rabbit by thousands for the market, and 
these leporines are further stated to be fertile both with the 
xxxvii. 54 
