370 G. CARL HUBER 
able. The uterine mucosa appears to have reacted normally; 
the decidual erypt in which this vesicle is lodged presenting nor- 
mal size and form, and the surrounding decidua normal strueture. 
The vesicle itself is retracted from the uterine epithelium, intact 
throughout the crypt, thus, does not appear to have attained the 
normal adhesions observed in normal vesicles of this stage. 
The four ova depicted in figures 3 and 4, appear to present a 
distinctive type of abnormal development, a type which is in- 
terpreted as showing retarded segmentation in certain of the 
cells of the 8-cell and perhaps 16-cell stage. All are found in 
Fig. 5 Four consecutive sections of the ovum of the albino rat showing 
abnormal development of the segmentation cavity 200. Rat No. 46, 6 days, 
14 hours, after insemination. 
uteri containing normal stages. The appearances presented, if 
correctly interpreted, speak in favor of a structural or metabolic 
defect inherent in the cells themselves and not primarily depend- 
ent on environment, pabulum, or embryotroph. 
ABNORMAL SEGMENTATION CAVITY FORMATION 
The following three ova have been grouped as showing irregu- 
larity in the formation of the segmentation cavity. 
In figure 5 are reproduced four consecutive sections passing 
through an abnormal ovum obtained from rat No. 46, 6 days, 14 
hours, after insemination. There were obtained from the uterus 
