PROLIFERATION AND REGENERATION 237 



concerning the nucleoproteids in cell division have been deter- 

 mined. Most important, perhaps, are the classical observations 

 of Miescher, who found that during the migration of salmon 

 up stream to the spawning grounds, during which time no food 

 is taken, the proteids of the muscular tissue become largely 

 transformed into the protamin type of proteid (characterized by 

 containing large proportions of the polyamino-acids, such as 

 arginin, histidin, and lysiu * ), which unite with nucleic acids to 

 form the abundant nucleoproteid of the spermatozoa and ova. 

 Whether such a transformation of proteids occurs in mamma- 

 lian cells during cell multiplication cannot be stated, but 

 certainly from some source an additional supply of nucleo- 

 proteid is derived. The nucleoproteids during karyokinesis 

 undergo a chemical change in that they become of a more acid 

 type (presumably through splitting off of part of the proteids 

 from the nucleic acid), which results in the characteristic increase 

 in affinity for basic dyes. This suggests the participation of an 

 enzyme in the process of karyokinesis, just as there seems to be 

 in the production of pycnosis in degenerating cells, but there 

 seems to be no conclusive evidence on this point. Gies 2 could 

 find no enzyme in spermatozoa that incites cell division in the 

 ova of sea-urchins (Arbauid). 



In metaplasia we have what may be interpreted as a chemical 

 alteration due to mechanical stimuli, e. g., the formation of 

 keratin by cells that ordinarily do not do so ; the deposition of 

 calcium salts and osteoid transformation of connective tissue in 

 rider's bone, etc. That such is the case, however, cannot be 

 positively stated from the evidence at hand. 



1 Concerning protamins, see re"sum by Kossel, Biochem. Centr., 1906 (5), 

 1 and 33. 



2 Amer. Jour. Physiol., 1901 (6), 54. 



