74 



J. DUESBERG. 



nuclear origin has been brought up again by Schreiner. Taking 

 for granted that Schreiner's description be accurate, nothing 

 proves however that his interpretation be correct, for the process 

 described as an expulsion of substance from the nucleus might 

 just as well be the reverse. And even if we accept Schreiner's 

 interpretation, we find that the question of the o-igin of the 



N, nucleus; above, idiosome with centrioles, surrounded by the apparatus 

 of Golgi. In the protoplasm, chondriosomes. 



chondriosomes has really not been touched, since chondriosomes 

 are present in all cells before the process which Schreiner de- 

 scribes takes place. 



Finally, the tremendous amount of work published in recent 

 years has revealed the presence of chondriosomes in practically 

 all cells, animal and vegetal. The only animal cells that con- 

 stitute an exception are the superficial cells of the epiderm: that 

 is, cells whose protoplasm is entirely differentiated and trans- 

 formed into a new substance. Whether chondriosomes exist 

 in the adult red blood-corpuscle might perhaps be questioned 

 also. It is not impossible that the presence of haemoglobin, 

 which is precipitated by the fixing reagents, be responsible for 

 the negative results obtained by most authors. But, one may 

 well ask, how can the cytologist decide whether he is in presence 

 of chondriosomes or not? A number of criteria may be applied 



