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G. CARL HUBER 



even in the 2-cell stage, more clearly shown in the 4-cell and later 

 segmentation stages, as will appear from further reconstructions 

 presented. It would seem to me reasonable to assume that these 

 cell masses are of such plasticity that they are molded by the 

 tubal mucosa rather than they would compress the mucosa and 

 maintain an inherent form. A number of segmented ova in 

 presumably the 6- and 8 -cell stages were removed from oviducts 

 by injection and studied in warm normal salt solution, in a liv- 

 ing state. In the warm normal salt solution the morula masses 



Fig. 13 Model of right oviduct of rat No. 50, 3 days, 1 hour. X 10. A short 

 segment of the upper end of the uterine horn, lower part of the figure, is included. 

 The fimbriated end and a part of the infundibulum removed in the drawing so 

 as to expose the underlying loops; their relative position is indicated in dotted 

 outline. The position of the four ova in the 4-cell stage, at the beginning of the 

 last loop of the oviduct, is shown as it seen through a transparent wall. 



presented a nearly spherical form, conforming to the conventional 

 illustrations of the same. In none of the sections of fixed material 

 of my series was this the case. The form of the cell mass, assumed 

 by the segmenting mammalian ovum in early stages of segmenta- 

 tion, therefore, seems to me a question more for academic dis- 

 cussion than one of fundamental importance. The right ovi- 

 duct of rat No. 50 (3 days, 1 hour) was reconstructed after the 

 Born method. This model is reproduced in figure 13, and 

 includes the uppermost end of the uterine horn. The oviduct 



