ARTIFICIAL PARTHENOGENESIS IN PODARK.E OBSCURE. 



239 



from the undivided portion and swim independently, forming 

 "dwarf embryos." So far as I can discover, their cleavage has 

 no resemblance to the normal. Their abnormal character is also 

 indicated by their nuclei, which have a very characteristic ap- 

 pearance, resembling closely those of abnormal eggs which oc- 

 casionally appear among a normally fertilized lot. The nuclei 

 are much larger and stain much more intensely than the normal 

 ones. Fig. 9 is from a living egg of this sort, and shows the 

 arrangement of the cilia. 



Besides these ciliated embryos are others, showing no indica- 

 tion of cleavage, but with well-developed cilia. Fig. 10 shows 



10 



ii 



FIG. 10. Ciliated, unsegmented embryo. Living material. 



FIG. II. Unsegmented embryo formed by fusion. Living material. 



one of these where the whole embryo is very much distorted, 

 but with a well-marked tuft of cilia. Staining with aceto-car- 

 mine after the above drawing was made, gave no indication of 

 cleavage in this embryo. 



Fig. i i shows a case of fusion of at least two eggs. This was 

 from an embryo slowly rotating around the end A as a pivot. I 

 was unable, however, to discover the distribution of the cilia 

 causing this movement. 



Fig. i 2 shows a still more interesting condition. Here, also, 

 there is apparently a fusion of at least two cells, but there is no 

 trace of cleavage. At n is possibly a nucleus. Around one 

 portion of the fused mass is a ring of cilia, occupying very much 

 the position, with respect to the cell, of the prototroch in its re- 

 lation to the trochophore. Not only are the cilia present, but 

 around the embryo, underneath the ciliated band, is an area free 



