214 
Katharine Foot and E. C. Strobell 
der das Auffinden einer Erscheinung für möglich hält, mit ganz andrer 
Intensität nach ihr sucht als der, der von vornherein von ihrer Unmög- 
lichkeit überzeugt ist.« 
In Protenor there can be no question that the chromatin nucleolus 
of the spermatocytes gives rise to the large chromosome of the first pro- 
pliase but we beüeve with Goldschmidt (1910), Wassilieff (1907) 
and Büchner (1909) that only a portion of the substance of the chromatin 
nucleolus is used for this chromosome and it does not therefore represent 
merely a persisting chromosome. One fact indicating this is the lack 
of agreement between the relative amount of chromatin in the nucleolus 
and in the reticulum in some of the preparations, with the relative amount 
of chromatin in the large chromosome as compared with the rest of the 
chromosomes. For example, compare the relative amount of chromatin 
in the accessory chromosome (at upper periphery of the group) in photo 43 
with the relative amount of chromatin in the chromatin nucleolus of 
photo 38. These facts are in accord with the many cases on record in 
which the chromatin nucleolus is figured as a structure much larger than 
the chromosome to which it gives rise. It seems to us the important 
point is whether the structure can be identified as a chromosome persisting 
from one cell generation to the next or whether it is the nucleolus of the 
cell having no closer relation to the chromosomes than has been claimed 
for other nucleoli. Both in Anasa tristis and Euschistus vanolanus we gave 
the evidence pointing to the conclusions that the chromatin nucleolus is the 
liomologue of the nucleolus of other cells and is not a persisting chromo- 
some. In both these forms we found evidence of the persistence of a 
nucleolus at an early prophase stage when all the chromosomes were 
present and coidd be demonstrated in a single photograph. The persisting 
nucleolus may represent only a part of the original structure and there- 
fore these facts would not demonstrate that the chromatin nucleolus and 
the chromosome are independent structures but they do seem to demon- 
strate that the chromatin nucleolus is not simply a chromosome that 
persists from one cell generation to the next. Identifving the cliromatin 
nucleolus as a nucleolus and not merely a persisting chromosome can 
be claimed also for the ovarian nucleolus of Protenor. The ovarian nu- 
cleoli arise by a Segregation of chromatin granules, a metliod which has been 
described as typical of the origin of nucleoli in general. This is demon- 
strated in photo 44, plate XVII. Further the great variability in size and 
form of this structure is another feature typical of nucleoli in general. 
Again, like Anasa tristis and Euschistus variolarius we find no other 
structure in these cells which can be interpreted as the nucleolus unless 
