ON THE DEVELOPMENT OF LINGULA ANATINA. 11 



cannot be looked upon as pathological, since they occur in eggs, 

 in which the various processes of maturation or of cleavage seem 

 to have gone on normally. 



In studying the living material I could observe in the ovum 

 (PL I., Fig. 1.) a translucent central portion of a light yellow 

 color corresponding to the yolk part, and a transparent peripheral 

 portion of a still lighter yellow color with a slightly greenish tint 

 representing the vacuolar layer. The outermost layer of vacuoles 

 is found to be a little thicker than the inner ones, all the vacuoles 

 being arranged or each vacuole being disposed with great re- 

 gularity. In one ovum it was actually observed that the first 

 polar body pushed up the vitelline membrane into a hillock, and 

 then under the first polar body was raised up, a still smaller 

 portion of cytoplasm which must, of course, represent the second 

 polar body (PL I., Fig. 1.). In section, only in three cases out 

 of several hundreds of eggs were polar bodies seen (PL IL, Fig. 

 20.). From this fact it seems most probable that the polar 

 bodies soon after they are cast off, disorganize and are absorbed 

 by the ovum. The exact time when the first polar body is 

 given off I could not positively determine, but as in the ova 

 just laid, the second polar mitosis has in most cases proceeded to 

 the meta- or ana-phases, it may be concluded with reasonable 

 accuracy that the first polar body is produced in a majority of 

 cases either while the egg remains in the body cavity or at the 

 moment after its deposition. 



As the metaphase of the second polar mitosis is the earliest 

 stage I have showing anything concerning the phenomena of the 

 formation of the polar bodies, I cannot at present give any 

 account of the changes antecedent to it. 



The second polar mitotic figure lies in a somewhat clear space 



