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R. T. Young 
from the digestive fluids of the kost. It is to be noted, however, that 
they are by no means restricted to this region, and that in some cases, 
notably in Cysticercus sp., from Evotomys g. galei, most, if not all, of 
the cells in the bodv show this character. If these differences are, as 
I believe, primarily due to nutriment, then the densely stained cells are 
those which, by reason of abundant nutrition, have been enabled to form 
an abundance of nucleo-albumin, which may perhaps in future be recon- 
verted into food for the tissues of the worm 1 ). 
It is, perhaps, not too far a cry to assume that these facts may throw 
some light on the theory of intra-selection ; for here we find, if my hypo- 
thesis be correct, two nearly adjoining cells, one of which has received 
more nutrition than the other, and is hence presumably better equipped 
for the »struggle of the parts« than its less fortunate neighbor. 
These nuelear differences might be attributed to faulty fixation 
and staining, were it not for the fact of their so common occurrence in 
variously fixed and stained preparations from different species, in many 
of which preparations such structures as flame cells appear with admir- 
able clearness, rendering this Interpretation highly improbable. 
That the developing »nucleoli« lying free in the cvtogenic proto- 
plasm or among the parenchyma Strands may have been cast out by 
some pre-existent nuclei, has not been disproven. It is exceedingly dif- 
ficult, however, to c-onceive of the migration of nuelear granules, and 
much more so to imagine the migration of nuelear membranes witliout 
granules, or of entire nuclei, along the slender parenchyma Strands con- 
necting cvtogenic masses. It is possible, of course, that the latter have 
broken away from other nuclei-containing masses either after or before 
receiving nuelear components from them. Tliis latter supposition would 
explain the case of those masses which are non-nucleated. But if this be so 
how are we to explain the undeveloped stage in which so many nuclei are 
found? Düring the Separation of these masses it is difficult to under- 
stand why the daughter nuclei should remain in the condition in which 
they were cast off from their parent nuclei, undergoing for a consider- 
able time no further development. Furthermore a process of division 
by which, in one case, a minute »nucleolus« was cast off from a parent 
nucleus, wliile in another case a part of the membrane only was budded 
off, would be an eccentric one to say the least. It may be argued, however. 
J ) A similar Suggestion has been made by Drzewecki (1904) regarding nuelear 
conditions in Monocystis. He says (1. c, p. 111), »Das Auftreten dieser Gebilde möchte 
ich auf außergewöhnlich reichliche Aufnahme von Nährstoffen und daraus resultierende 
Zusammenballung der ehromatinähnlichen Körnchen zurückführen «. 
