1908.| 2 the Placenta and Fetus of the Pregnant Rabbit. 267 
When the two parts of the placenta are pulled apart, the delicate peninsule 
are left attached to the fcetal placenta. In the latter no glycogen was 
observed by Chipman at any period of pregnancy. Hence the glycogen’ 
obtained from the foetal placenta is not, as might appear at first sight, 
actually in the fcetal tissue, but really belongs to the maternal placenta, and 
forms that part most intimately related to the foetus. 
By analysing the two parts of the placenta obtained by mechanical 
separation, information is gained on the changes in the glycogen of two 
different parts of the maternal placenta. The bulk of the maternal placenta 
contains the glycogen of the zone of separation (A) and of the region of the 
uterine sinuses (B). This part of the glycogen may be called for convenience 
the “distal glycogen.” The glycogen in the peninsular projections (C), which 
are left attached to the foetal placenta after mechanical separation, may be 
called “proximal glycogen.” It is estimated by analysing the fcetal placenta, 
as no glycogen can be demonstrated histologically in the foetal placenta 
itself. | 
It is possible that a small part of the glycogen extracted from the fcetal 
placentze in this way may actually belong to the cells of the fcetal tissue, as 
the villi, like the early foetal liver, may possess a small quantity of glycogen 
not demonstrable histologically. The colour reaction with iodine was tested 
in several cases, because it has been found that the tint is violet-red with 
elycogen obtained from foetal tissues instead of the usual reddish-brown. In 
no case was there any difference from the colour obtained with maternal 
glycogen. Hence most of the carbohydrate extracted from the fcetal placenta 
was probably maternal. We shall see later that very small quantities of 
glycogen may be present even when histological methods fail to reveal it, but 
in any case the amount could not be large enough to affect materially the 
results obtained. 
The results obtained from the analysis of parts A and B of the maternal 
placenta are given in Table II. 
The maternal placenta has, in every case, a considerable percentage of distal 
glycogen, and one that is in the earlier stages quite comparable with the 
percentage obtained in a healthy adult rabbit’s liver. It rises from the 14th 
to the 18th day. From the 18th to the 22nd day it remains fairly constant; 
then there is a continuous decrease each day until the end of gestation. 
Even at the 29th day there is an appreciable amount of glycogen, which, as 
histological examination shows, is almost entirely situated. at the zone of 
separation of the placental lobes, and is probably not destined for the foetus. 
The most obvious phenomenon in the decidual cells of the rabbit is the 
presence of glycogen at a time when the fcetal liver cells store only the 
