The Somatic Auclei of Certain Cestodes. 
157 
in the haematoxylin while others stain red in the eosin 1 ). This staining 
difference is probably due to the greater or less amount of chromatic 
material in different cells. But this explanation will not apply to the 
difference between the more uniformly stained cells and those in which 
a fairly definite mtcleus is differentiated. In the former I believe the nu- 
clear matter is diffuse, and in the latter aggregated in more or less definite 
nuclei. Distributed thru the sub-cuticula are small darkly staining gran- 
ules varying in size, which I believe represent developing nuclei. An 
examination of2000 nuclei 2 ) has failed to show any mitosis in this worm 3 ). 
General Considerations. 
In my discussion of cytogenesis and nuclear significance in Cysti- 
cercus pisiformis (1. c., p. 233) I have called attention to the few recent 
writers who have suggested a de novo origin of nuclei 4 ). Their results have 
not been accepted as vet and one of them (Henking) has retracted his 
original Claims. While the great mass of observations on cell divisions 
both direct and indirect, all tend to establish the universality of the law 
»omnis cellula e cellula«, still the many biological »laws« which have 
been shattered in the past should lead us to be cautious about denying 
the possibility of exceptions to such of these laws as are still intact. It 
was formerly held by many cytologists that amitosis was an abnormal 
process occurring only in cells which were destined to destruction. He 
would indeed be rash who would maintain such a view today. With 
the degenerate group of Cestodes I believe that we must go a step further 
and admit at least the probabilitv, if not the certainty, that here nuclei 
arise, not only bv division of pre-existent nuclei, but also as a direct 
physiological modification of a non-nuclear cytogenic mass. 
If we admit the evolution of living from non-living matter, itis surely 
most logical to conceive of the first organic being as one composed of 
undifferentiated protoplasm from which, in the course of evolution, a 
nucleated cell has arisen. Furthermore it seems logical to suppose that 
the primitive nucleus arose, not as a eollection of biophors, pangens, 
plastidules, or other hypothetical units, for the purpose of transmitting , 
the hereditary qualities of parent to offspring in an organism whose de- 
x ) See table of stains, p. 141. 
2 ) See footnote 1), p 145. 
3 ) See footnote 3), p. 155. 
4 ) An author not mentioned in my previous paper is Drzewecki (1904) who 
has described the degeneration of the nucleus in Monocyslis and its subsequent de novo 
regeneration. He has not however described nuclear multiplication by this method. 
