292 On the Teeth of certain Ruminants. By M. V. Pietkiewiez. 
as the wild boars (Sangliers) have, that is to say the same number 
as the pachyderms. Thus, among the ruminants, we already know 
of fossil species having the same dental formula as the pachyderms, 
and of living species whose formula is almost identical; the dis- 
covery of Goodsir, by giving to ordinary ruminants, such as the ox 
and sheep, at a certain period at least of their lives, the same for- 
mula as that of pachyderms, permits us to associate these two 
groups. One set of naturalists sees in this one of the results of 
their hypothesis upon the unity of plan in nature. Another set 
sees in it a confirmation of their transformist theories, and explains 
the abortion of these organs by their non-usage, and the successive 
confirmation of this anomaly by “ adaptation” and “ heredity.” 
I was therefore surprised when, in endeavouring to verify an 
opinion which was so creditable to science, I found nothing what- 
ever to justify it. In a long series of preparations made upon the 
embryos of the ox and the sheep from the earliest period of em- 
bryonic life to the period when the foetus is 30 centimeters long in 
the sheep, not only have I never found the presence of follicles, 
but I have not even found a trace of the epithelial lamina, the 
beginning of all follicular development. 
Goodsir’s error was conceived through the false notion he had 
formed of the development of the follicles, and in the commence- 
ment of my investigations I had the same idea. In sections made 
properly at the anterior part of the upper jaw of the ox or sheep 
one finds in fact on each side of the median line an epithelial sac, 
which detaches itself from the buccal mucous membrane to bury 
itself in the jaw. The mucous layer of Malpighi uninterrupted forms 
itself an external lamina, whilst on its interior is found a polyhedric 
epithelium like that of the middle layers of the buccal epithelium. 
Thus formed this little sac appears to constitute the commencement 
of the follicle as Goodsir imagined it. But in continuing to make 
on the same jaw a series of sections going farther and farther from 
the anterior part, one sees the little sac lose its relations with the 
buccal mucus, and take the form of a circular canal for the mucus 
of the nasal fosse. Soon appears around this canal a cartilaginous 
belt, then at its upper part is a pad (bourrelet) containing vessels, 
and then one has before him Jacobson’s organ as Gratiolet 
described it. There is then nothing that can be compared even 
distantly to the germs of canines and incisors. If it is possible to 
conceive of Goodsir’s error in face of the little epithelial sae pro- 
duced by section of the buccal extremity of Jacobson’s organ, one 
finds nothing to justify him in affirming the presence of three 
incisors, of one canine, and of one molar tooth in this region.— 
Comptes Rendus, March 12, 1877. 
