126 G. CARL HUBER 



able. The uterine mucosa appears to have reacted normally; 

 the decidual crypt in which this vesicle is lodged presenting nor- 

 mal size and form, and the surrounding decidua normal structure. 

 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 X 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 



