PLASMA-STRUCTURE IN EGG OF HYDRACTINIA 215 



still different method of chromatin-emission is described by Small- 

 wood ('09) in Hydractinia. Soon before maturation small parti- 

 cles of chromatin leave the nucleus and wander into the proto- 

 plasm. Smallwood says, "The reason for regarding them as 

 chromatin is because they give the same color reactions as similar 

 shaped bodies in the nucleus, and for the further reason which is 

 obvious in figure 1, namely, the actual migration of the chromatin 

 from the nucleus." An exactly similar chromatin-emission is 

 described by Smallwood ('07) for Pennaria, taking place here, 

 however, after maturation rather than before. Also in this form 

 the chromidia are stated to arise from both male and female 

 germ-nuclei. In these two Hydroids the protoplasmic chromatin 

 is connected with neither yolk formation nor differentiation. As 

 will be shown in the next section, I have traced the nucleus in 

 Hydractinia through the growth-period, the reappearance of 

 the chromosomes and maturation stages, and in no case are bodies 

 of the type described to be found. From Smallwood's figures, it 

 is evident that the fixation is defective, since a very strong coagu- 

 lation net is present which does not appear with good fixation. 

 It seems to me the bodies in question may well be artifacts. 



Trinci ('07) has described basophiUc granules in the oocytes of a 

 number of Hydroids, which he considers as a differentation of 

 the protoplasm brought about by the influence of the nucleus 

 and as belonging in the same category as chromidia, mitochondria 

 or plastosomes. The granules disappear during the development 

 of the egg. 



Van Herwerden ('13) has recently tested Schaxel's hypothesis 

 of the nuclear origin of the basophylic granules by the use of 

 nuclease. After treating the mature echinoderm egg (in which 

 mitochondria are visible in life) with a preparation of nuclease, 

 he finds that the mitochondria (basophilic granules) have disap- 

 peared. He concludes that the mitochondria are a nucleinic 

 acid compound and therefore properly chromidia. Since in the 

 young, living egg he can see none of the basophilic granules which 

 appear in fixed material, he believes the latter are artifacts. Un- 

 like Schaxel, however, he holds the mitochondria to be developed 

 from this basophilic substance, since it is also a nucleinic acid 



