122 RESPONSES OF CELLS ON THE BIOLOGICAL LEVEL 



Artificial Parthenogenesis 



In Fig. 20 we see arranged a list of agents which are com- 

 petent to cause artificial parthenogenesis. The first group 

 including substances such as fatty acids, saponin and 

 organic bases, have in conamon the possibility that they 

 may act upon the surface of the cell causing, as J.Loeb 



Superficial cytolysis 

 (fatty acidi, saponin, etc) 



Pricking 



Ultraviolet light 



». Permeability change 



(change in resting potential?) 



Dehydration by 

 hypertonic! 



Dehydration after_ 

 hypotonicity 



Cold- 



Gelation in 

 endoplasm 



■Aster formation 

 Aster growth 



Cell division 

 Fig. 20. Mode of action of agents causing artificial parthenogenesis 



suggested, a superficial cytolysis to arise, or to become 

 incipient. With some species activation may also be 

 secured by totally different methods such as pricking, 

 the use of ultra-violet light, treatment with hypertonic or 

 hypotonic solutions, and treatment at low temperatures. 

 So far as is known, there is no common mechanism which 

 can be acted upon by these diverse agents and processes. 

 But all the reagents ultimately lead to cell division, and 



