Amitosis in tlie Ovary of Protenor belfragei and a Study of tlie CliromatinNucleolus. 213 
In tlie aniitotic division of Protenor the large nucleus may constrict 
off smaller pieces, the larger amount of nucleolar chromatin being re- 
tained in the original nucleus (photo 25) but the smaller cells also have 
each a portion of the same chromatic substance — the division is there- 
fore in no way comparable to the differential divisions of Dytiscus. 
In Protenor it is evident that the substance forming the chromatin 
nucleolus is of the same nature as the chromatin which forms the chromo- 
somes for the two large chromosomes are evolved from part of the substance 
which at one stage forms a nucleolus and further there is evidence that 
from a like nucleolar structure may be evolved not only the two large 
chromosomes but the entire group of chromosomes typical of this form 
(photos 5 — 12). In Protenor therefore the chromatin nature of this sub- 
stance is evident and this feature it has in common with Giardina’ s inter- 
pretation of the nature of the substance which forms the ring of Dytiscus. 
Both Debaisieux and Günthert however insist that the substance 
forming the ring of Dytiscus can at an early stage be differentiated from 
the chromosomes. Günthert interpreting it as “Zerfallsprodukte” of 
the chromosomes and Debaisieux claiming for it a nucleolar rather than 
chromatin nature. He says: «Quelle que soit son Organisation, cet element 
offre une colorabilite nettement distincte de celle des chromosomes. Apres 
coloration ä rhematoxyline de Heidenhain et au rouge Congo, il est 
colore en rouge, tandis que les chromosomes sont colores en noir» p. 212. 
«Rappeions d’abord qu’une fois apparue, la masse chromatique, — et 
ici nous n’avons fait que confirmer Giardina, — est transmise ä travers 
quatre cineses successives ä l’ovocyte. Seulement, pendant le grand 
accroissement de l’ovocyte, contrairement ä ce que decrit Giardina, la 
masse chromatique se fragmentant en nombreux corps d’aspect nucleolaire, 
fournit tout le reseau qui remplit la cavite nucleaire, les chromosomes 
diplotenes n’occupant qu’une portion restreinte de l’aire du noyau. Par 
consequent, la masse chromatique fournit, en somme, un reseau ana- 
logue ä celui qui dans la plupart des oeufs remplit la vesicule germinative, 
en dehors des chromosomes persistants. Remarquons en second lieu 
que l’ovocyte du Dytiscus , ni pendant son etape synaptique, ni pend- 
ant son grand accroissement, ne possede, contrairement ä la plupart des 
oeufs, de veritable formation nucleolaire» p. 226. 
Disagreement in the observations and conclusions of investigators 
studying the same subject is a familiär fact and may it not be due largely 
to variability of the structures under discussion as well as to the bias 
of the investigator in favor of one set of facts. Perhaps however none of 
us can plead not guilty to Goldschmidt’s accusation, »Daß derjenige, 
