266 G. F. Barker—Physiological Chemistry. 
cess; it is also changed into sugar very readily by the action of 
acids and ferments, and in a word, possesses all the characters of 
that obtained from the liver or the placenta. The horny appen- 
ges of the skin, too, contain glycogenic cellules, which disap- 
pear as development progresses. In the skin itself, the glyco- 
genic matter disappears rapidly; being absent toward the 
third or fourth month of intra-uterine life, in calves 25 to 30 
centimeters long, in which well defined epithelium is present. 
Even when absent from the cellules, it is found infiltrated into 
the skin. Mucous surfaces also, at certain stages of develop- 
ment, show glycogenic cellules. With embryo pigs, calves, or 
ambs 3 to 6 centimeters long, they may be observed in the 
mouth, tongue, pharynx, stomach, large and small intestine, 0c- 
curring in the epithelium surrounding the villosities. The mu- 
cous surfaces of the air passages, and also of the genito-urinary 
passages show the same fact. It thus appears that all the 
exterior limiting surfaces possess during foetal life, before the 
: : P 
ing their development. The osseous and nervous systems con 
tain no glycogenic matter at any stage ; the brain, the spinal 
cord, the bones—freed from periosteum—and the cartilages, 
2 to 4 centimeters long, embryonic cellules not colorable b 
iodine are found in the positions soon to be occupied by mus 
| : 5 
this is best seen in the foetus of the cat, As the fiber devel 
i a becomes striated ; but the glycogenic matter thon 
essen at amount is not absent, but seems infiltrated into 
tissue. | no case did this giyeogenic matter appe er 
: Mules. This 
