5G2 Chas. W. Hargitt 



to nie to be associateci witli maturation and fertilization phenomena, 

 but the latter feature must be eliminateci in the preseut instanee, 

 since in the absence of male specimens it was obviously out of the 

 (luestiou. Whether any of the immediate phases of maturation may 

 havc been involved is likewise open to doubt, since I was unable 

 to demonstrate any of the ordinary features of this process, either 

 in living eggs or in those sectioned and stained. Intimately as- 

 sociated with these changes were nuclear modifications of a more 

 or less remarkable character. Prominent among them is the disso- 

 lution of the nuclear membrane which occurs shortly before the 

 birth of the medusa and the discharge of the eggs. Following this 

 there occurs a marked decrease in the mass of the nuclear sub- 

 stance, ])robably due to the loss of nuclear sap, or a dispersal of 

 matter through the cytoplasm, so that the nucleus measures only 

 about half that of the ovarian egg. Of still greater importance is 

 the change which occurs in the chromatin network of the nucleus, 

 which appears to wholly disintegrate and to disperse through the 

 cytoplasm. Not the slightest trace of chromosomes or chromatin 

 substance can be demonstrated in the nuclei or cytoplasm at the 

 time of the liberation of the medusa. The nucleus itself, greatly 

 reduced in size, may still be seen as a definite area of very homo- 

 geneous texture, but indefinitely merging info the surrounding cyto- 

 plasm,- there being no trace of nuclear membrane. 



Prior to these later nuclear changes is another involving the 

 nucleolus, which during the earlier ovarian history is a body of 

 conspicuous character and strong staining qualities. In sections of 

 eggs of about the conditions shown in Fig. 8, or sometime prior to 

 the complete dissolution of the nuclear membrane and perhaps iu- 

 citing it, it is ([uite common to find nucleoli migrating bodily from 

 the nucleus iuto the cytoplasm where they seem later to disintegrate 

 and mingle with it. In several sections double nucleoli Avere fouud 

 in a single nucleus, as shown in Figs. 8 and 9. In almost every 

 case of this sort one of these bodies appeared appreciably smaller 

 than the other, and often somewhat distorted in shape, as may be 

 observed in the figures just cited. 



Yacuolation of these nuclei was not an infrequent phenomenon. 

 It usnally consisted of one, or rarely two, slightly refractile vesi- 

 cular iMtdic'S occupying an excentric position in the nucleolus. Careful 

 search was made for evidence of directly dividing nucleoli, but with- 

 out success. The occurrence of two in a giveu instance is probably 



