1908.] in the Placenta and Fetus of the Pregnant Rabbit, 279 
tissues. In the case of Rabbit F, the maternal part of the placenta is not 
diminished in weight, although its glycogen store has been greatly reduced, 
while the foetal part of the placenta, which normally is free from glycogen, is 
greatly reduced in weight. 
The results obtained by treatment with phloridzin confirm the conclusions 
which we have drawn from our observations on spontaneous cases of retarded 
growth. They show that the growth of the fcetus is dependent upon glycogen 
in such a way that the glycogen is not actually present in the growing cell, 
but that the foetus draws upon a deposit which is laid down at first in the 
* maternal part of the placenta and is transferred in the last week of pregnancy 
to the liver of the foetus. 
F. The Glycogen-splitting Ferment of the Placenta. 
Glycerine extracts, both of the maternal and of the foetal part of the 
rabbit’s placenta, were found to have a powerful hydrolytic action on 
glycogen. This action was destroyed by heating the extracts. Extracts of 
sheep’s placentze showed, even on qualitative examination, a very much less 
marked glycogen-splitting power. 
The activity of the ferment was measured quantitatively by determining 
the amount of sugar split off after incubating a mixture of measured 
quantities of the glycerine extract and of a solution of glycogen, purified by 
repeated precipitation with alcohol. Toluol was added. After 24 hours the 
glycogen was precipitated by alcohol and the amount of sugar estimated in 
the filtrate by Allihn’s method. In order to account for the sugar of the 
blood present in the glycerine extracts, control experiments were made 
with the heated extract. In these controls only very small and almost 
constant quantities of cuprous oxides were found, the figures ranging from 
0:001—0:004 gramme. These figures were subtracted from the results 
obtained in the digests, and in this way a measure of the activity of the 
ferment was obtained. 
The results obtained for the placenta of the rabbit are given in the 
following table :— 
Glycogen-splitting Ferment in Placenta of Rabbit. 
Maternal placenta. Feetal placenta. 
Day of gestation. Weight of Cu,0. Weight of Cu,0. 
(Difference.) (Difference. ) 
gramme. gramme. 
17 0 -0218 0 :0328 
21 0 0040 0 1463 
24, 0 0424, 0 -0476 
30 0 °0196 0 0237 
VOL. LXXX.—B. Z 
