366 G. CARL HUBER 
be projected with any degree of certainty. The most charac- 
teristic vesicle showing this phenomenon is presented in figure 3, 
and is taken from rat No 58, 5 days after insemination, the 
uterus of which contained seven blastodermic vesicles showing 
early stages of development, four of which are reproduced in 
figure 22, Part I. In A and B of figure 3 are reproduced two 
consecutive sections of a series of five sections of 10 uw thickness, 
includ‘ng this ovum. In the lower part of this ovum there is 
found a small segmentation cavity, bounded by cells which 
present normal appearances. The roof of this vesicle is shghtly 
Fig. 3. Early stages of the blastodermic vesicle of the albino rat, presenting 
evidence of irregular or retarded segmentation. X 200. Rat No. 58, 5 days after 
the beginning of insemination. 
Fig. 4 Three ova of the albino rat, showing early blastodermic vesicle stages, 
in each of which certain of the cells suggest irregular or retarded segmentation. 
< 200. A, rat No. 64, 4 days, 14 hours, after the beginning of insemination. B, 
rat No. 68, 4 days, 15 hours, after the beginning of insemination. C, rat No. 
54, 6 days, 16 hours, after the beginning of insemination. 
folded and compressed, as a consequence of which the roof wall 
in the sections figured is presented in part as seen in surface 
view. In the floor of this vesicle there is to be observed, sur- 
rounded by other smaller cells, one large cell, of nearly spherical 
shape, having a diameter which is three or four times as great 
as that of the majority of the surrounding cells. The protoplasm 
of this large cell stains less deeply than does that of the majority 
of the other cells constituting the floor of the vesicle. Its nu- 
cleus is relatively large and slightly lobulated, so much so that in 
the section of it shown in A of this figure, in the optical section 
sketched, the nucleus appears as three separate nuclei, in reality, 
