OBSERVATIONS ON STRUCTURE OF CELLS AND NUCLEI. 175 



these reagents than they are in the fresh state or by chromic 

 acid. 



Flemming, in the above paper, expresses dissent from the 

 view of a connection between the intracellular and intranu- 

 clear networks ; the same opposition is expressed by W. 

 Schleicher in a paper on the division of cartilage-cells (^Archiv 

 Mikrosk. Anatomic,' p. 261), both he and Schleicher declaring 

 the nucleus to be something quite separate and independent 

 of the cell-substance. From my own experience as described in 

 the foregoing pages, I must most decidedly oppose this sepa- 

 ration of nucleus and cell-substance, and I would particu- 

 larly draw attention to the remarkable observations of 

 Strieker (' Sitzungsb. d. k. Akad. d. Wiss./ June, 1877) on 

 colourless blood-corpuscles of frog and newt. Strieker ascer- 

 tained the contractility of the intranuclear network and the 

 continuity of this with the cell-substance, as well as the im- 

 portant fact that the membrane of the nucleus disappearing, 

 its network becomes fused with the cell-substance, and 

 vice versa, the membrane appearing a part of the cell-sub- 

 stance becoming enclosed in it as nucleus. The nucleus is 

 therefore a portion of the cell- substance specially differen- 

 tiated by the presence of a membrane. 



I have repeated the observations of Strieker on the large 

 pale, and also on the small uninuclear corpuscles of newt's 

 blood on the warm stage, and I can fully confirm his state- 

 ment that the internuclear network, especially of the latter, 

 is contractile, and that the substance of the nuclei of the 

 former becomes fused with the cell-substance, this membrane 

 disappearing on one side or the other. The cell-substance 

 is a minute network of varying distinctness. 



