230 CORA J. BECKWITH 



V. SUMMARY 



1. The bulk of the evidence from staining reactions and 

 morphological conditions indicates that those protoplasmic 

 granules in Hydractinia which often take the chromatic stains 

 are not extruded from the nucleus as such, and points to their 

 formation de novo throughout the protoplasm. The granules are 

 therefore not comparable to the chromidia of Hertwig and the 

 term 'pseudochromatin-granules' is justified. 



2. There is no evidence of formed material passing through the 

 nuclear membrane into the protoplasm either early (Schaxel) or 

 late (Smallwood) in the growth-period. Globules, which may be 

 mistaken for such material, are formed during the growth-period, 

 flattened against the nuclear wall, but their staining reactions 

 under certain conditions differ from those of chromatin. 



3. We are still unable to differentiate with certainty by any 

 of the above methods, the nuclear derivatives in the protoplasm, 

 i.e., staining tests cannot be relied on as tests for chromatin. 



4. The yolk is formed in Hydractinia directly from the scattered 

 pseudochromatin-granules and not from nests of granules. 



5. The pseudochromatin-granules correspond in a general way 

 to the yolk-nucleus of many other forms.. Here the granules 

 are neve'r gathered into a distinct body. 



6. The pseudochromatin-granules are completely used up in 

 the formation of the yolk ; that is, none, as such, are left in the 

 protoplasm between the yolk-spheres (intravitelline chromatin 

 of Schaxel) to determine further differentiation. 



7. The yolk is not formed from mitochondria in Hydractinia 

 and there is no yolk-nucleus consisting of mitochondria. 



8. The mitochondria are not of nuclear origin in Hydractinia, 

 but arise de novo in the protoplasm after the formation of the 

 yolk has begun. I find no evidence of multiphcation of mito- 

 chondria by transverse division, or of their genetic continuity 

 from one cell-generation to another. 



