PLASMA-STRUCTURE IN EGG OF HYDRACTINIA 227 



disappeared before the reappearance of the chromosomes (fig. 

 23), or, as is more common, it ma}'' be disappearing as the chromo- 

 somes are reforming (fig. 29,, a). 



Because of its staining reaction, the nucleolus was at first 

 thought to be chromatic. Since the nucleus, throughout the 

 greater part of the growth-period, is non-staining with basic dyes 

 while the nucleolus takes these stains intensely, it at first seemed 

 evident that the chromatin which .is to form the chromosomes is 

 stored in the nucleolus during this stage, a condition described for 

 a number of forms.® This conclusion proves to be unfounded after 

 further staining tests, since the nucleolus does not always take 

 the characteristic chromatin-stain (table 1.) For example, in 

 Hermann's saffranin methyl-violet stain, the nucleolus is red 

 while the chromatin of the 'resting' nucleus is violet. Also, in 

 Bensley's acid fuchsin methyl-green stain the nucleolus stains 

 with the fuchsin or plasma stain. Again, in x^uerbach's stain, 

 which ordinarily stains the chromatin green, the nucleolus is 

 stained blue. The strongest evidence that the nucleolus is not 

 chromatin is given by Benda's stain, after which the chromatin is 

 yellow-brown and the nucleolus ^dolet. This point is confirmed 

 by Dublin ('05) who finds decisive proof with Auerbach's stain 

 that the basic staining- nucleoli of Pedicellina are not chromatin. 

 The nucleolus in Hydractinia has at no time any direct connection 

 with the chromosomes as described by Guenther ('03) and 

 Dublin ('05). There is no^ evidence then that the disappearance 

 of the nucleolus at the time of the reappearance of the chromo- 

 somes bears any relation to the same. From the above description 

 of the nucleolus in Hydractinia, it is evident that no fragmentation 

 of the nucleolus contributes to the formation of basic granules 

 (pseudochromatin-granules) which lie in the protoplasm, as Har- 

 gitt finds in Campanularia. 



^ Chromatic nucleoli have been described among hydroids in Forskalia and 

 Agalma by Schaxel ('11); Gonionemus, Bigelow ('07); Campanularia, Hargitt 

 ('13); Cubomedusa, Conant ('98) Hydra, Downing ('09); Gonothyrea, Wulfert 

 ('02). Gtinther ('03) finds the nucleolus in the echinoderm egg forming out of the 

 nuclear net, and the chromosomes reappearing from the nucleolus. 



