The Cytoplasm as Specific Substrate 201 



It is possible that Correns' work on Cirsium (last 1928) also belongs 

 here. As the complication of monoecism is again involved, in a rather 

 confusing way, we may only say that some sexualizing cytoplasmic 

 function is proved, which will be taken up in more detail later. The 

 conclusion is that a relatively simple chemical conditioning of the 

 cytoplasm, which sets the pace for all of sexual differentiation, may 

 be inherited cytoplasmically ( of course including the interplay of this 

 condition with genically controlled features); or the chemical condi- 

 tioning may be induced in the cytoplasm of the egg by genie action 

 of different kinds in individual cases, 



B. DAUERMODIFIKATION 



The last examples involve real cytoplasmic, generalized action, 

 which we could describe simply as the action of a specific cytoplasmic 

 constitution involving the entire plasma of the cell and producing a 

 rather generalized effect upon developmental processes, as opposed 

 to the highly specialized effects of most genie actions. With Wettstein 

 ( 1928?? ) , also followed by Caspari ( 1948 ) , we can call this a plasmon 

 action or an action of the plasmon type. (It would be incorrect to say 

 that the cell contains a plasmon as a nucleus contains genie material. 

 There is unfortunately much loose thinking about this.) Before dis- 

 cussing the problem further, a brief reference must be made to a 

 phenomenon called by its discoverer Jollos ( 1921 ) Dauermodifikation. 

 Quoting Sonneborn (1951a), "Dauermodifikationen are traits which 

 are induced by environmental conditions and then manifest temporary 

 cytoplasmic inheritance. After a time, under the original conditions, 

 the induced trait disappears and the original trait reappears." These 

 traits involve morphological changes induced in animals by temper- 

 ature action which disappear within a few generations after apparent 

 inheritance through the maternal cytoplasm. Specific examples are as 

 follows: Drosophila, Plough and Ives (1935); morphological changes 

 in bean leaves, produced by chemical treatment, Hofmann ( 1927; see 

 also Sirks, 1937); physiological changes in Paramecium in suscepti- 

 bility or resistance to poisons, especially studied by Jollos (1913ff. ); 

 immunobiological changes in Paramecium, studied by Sonneborn 

 (1943fe). Caspari (1948) also includes the so-called milk factor in 

 tumor production. 



Though the facts appear rather consistent, their explanation is not 

 completely clear. One idea (the original interpretation by Jollos) is 

 that the external agent produces directly or by reaction products a 

 chemical condition of the cytoplasm, say a substance, which in the 



