160 TRICHOLOGIA MAMMALIUM; 
Why, then, hesitate to acknowledge two species of Sheep, the race of one of which is 
permanently covered mith hair, and that of the other as permanently covered with wool? 
Especially if, as has been shown, the difference between these intezuments is not 
merely one of color and marking. (as in the cases of the Horse and the Ass, and the Horse 
and the Ass and the Zebra,) but wltere the shape, dérection and inclination of the pile is 
different—where the disposition of the coloring matter is remarkably different; and, above 
all, where the number, shape, position and mode of adherence of the scales of the cortex 
are so entirely different as to render the one altogether unfit for felting and fulling, and 
not hable to shrink, while the other is admirably adapted to felting and fulling, and lable 
to shrink. ‘Take a!! these things into consideration, and then say whether there is not, at 
least, as much ground for believing these two animals to constitute two species, as there 
exists in regard to the unity or plurality of the humps of the Camel, or of the horns of 
the Rhinoceros. And then, again, remember that. to establish this modification, there 
must be a difference of organization—a difference in the functions which the apparatus of 
each kind have, respectively, to perform; for instance, the fibres and cortéx of the wool, 
while they subserve all the ordinary purposes which they do in hazr, are also the medium 
of conveyance for the coloring matter of the former integument, while that of the latter 
flows in a central canal. 
“Species of plants (says Mills) are not only real kinds, but are, probably, all of them 
real lowest kinds, or infine species.” And he adds, “I say probably, (not certainly, ) 
because this is not the consideration by which the botanist determines what shall or shall 
not be admitted as a species; but which, consistently with experience, mzght have been 
produced from the same stock.”’* 
So that, in the present instance, (seeing that the same law prevails in the animal com- 
monwealth,) where the inquiry is ‘‘ whether the hairy Sheep and the woolly Sheep are or 
are not two distinct species?” we are not bound to show, absolutely, that they are 
descended from different parentages ; but only that, consistently with experience, they 
might have been descended from different parentages. And after having shown the diffe- 
rence between hair and wool, and having pointed out the character of the discrepancies 
upon which zodlogisis have been in the habit of creating species, we would confidently 
inquire, whether any naturalist who had presented to him two newly-discovered mid 
animals, otherwise alike, but one of which had always produced wool and the other one 
hair, would hesitate to consign them to two specific departments! And if he would not, 
then why, in the case now before us, should we allow habit, born in ignorance and 
nurtured in stubborness, to prevail over the dictates of reason and experience? 
Let it not be supposed, from what has been hitherto said, that too little attention has 
been paid to the laws of physiology, for we do not believe, that the zodlogical and physi- 
ological, and even the embryological meanings of the word speczes materially differ. ‘The 
author last cited remarks that, ‘1t seems to be a law of physiology that animals and plants 
* By the adoption of this rule no inconsistency is introduced, for, (as this learned author shows,) this distinction in most 
(and probably in all) cases happily accords with the other. 
