THE RESTING NUCLEUS 3 



living resting nucleus, which are almost undoubtedly 

 chromosomes, although highly hydrated and almost 



M.n. 



Fig. 1. — Unusual types of nuclei ; a in a vertebrate marrow- 

 cell ; 6 in one of the spinning gland cells of Platyphylax 

 (Caddis-fly) ; c in a spermatogonium of the grasshopper 

 AiUarchea ; d in a spermatogonium of the Bush-Cricket 

 Pholidoptera griseoaptera. In c each chromosome lies in 

 a separate nuclear membrane, in d only the sex-chromo- 

 some lies in a separate membrane. C^t. = cytoplasm ; 

 C.v. = chromosomes lying in nuclear vesicles ; X = 

 X - chromosome . 



invisible, due to their having nearly the same refrac- 

 tive index as the nuclear sap. That the chromosomes 

 do actually persist through the resting stage is 



