Manchester Manoirs, Vol. I. (1906), No. i». 27 



supports such an idea. But our knowledge of the micro- 

 chemistry of the cell is still too meagre to arrive at absolute 

 certainty on this and other points. 



The usual preconceived idea of the unchangeable 

 nature of the nucleus does not rest upon a solid foundation. 

 As Gruber (40) in the Protozoa, Hickson (50), Hill (51), 

 and Hargitt in the Coelenterates, Henking in Insects, and 

 many others in other groups, have all shown that the 

 nucleus in many cases loses its compact character and 

 fragments, nor is this a pathological condition, but quite 

 normal. In some cases the chromatin granules remain 

 clustered together, in others they become scattered 

 through the cytoplasm of the ovum, either remaining in 

 that condition, or collecting later into definite nuclei. 

 These facts do not support any theory of the individuality 

 of chromosomes, as put forward by Rabl (80), Baumgartner 

 (6), Boveri and others. Nor do they furnish evidence for 

 any hypothesis which considers the chromosomes only as 

 the bearers of hereditary characters. 



The evidence available on the cytology of partheno- 

 genesis in insects is too small and too diversified at 

 present to allow us to draw any conclusions on questions 

 of heredity and sex, about which we know little. It is 

 certain, however, that the accumulation of observations 

 and facts on this subject and not of hypotheses and 

 theories on insufficient facts, will be the only way in which 

 we shall be able to elucidate those, at present, unsolved 

 riddles. 



