HAECKEL AND PFLUGER 85 



designate the purely speculative, primary structural units of 

 living substances, ' the idioplasm ' of Naegeli and Weismann, 

 ' the biogenes ' of Verworn, ' the plastomes ' of Wiesner, ' the 

 protomeres ' of Heidenhain, ' the gliodes ' of Botazzi, ' the 

 vitules ' of Meyer, * the vitaids ' of Lepeschkin, ' the mole- 

 culobionts ' of Alexander and Bridges, etc., etc. 



Naturally such authors tried to solve the problem of the 

 origin of these hypothetical units of life, substituting this for 

 a solution of the problem of the origin of life itself. That, 

 however, did not carry them any further forwards, as the 

 one problem presented no less difficulty than the other. 



As early as the end of the nineteenth century A. Weis- 

 mann^"'^^ put forward his theory that every organism contains 

 a special germinal substance which does not change in the 

 course of life (' idioplasm '). In particular, this is regarded 

 as carrying the hereditary endowment and other character- 

 istics of the organism. All the rest of the body of the organism 

 (' soma ') is merely a lifeless receptacle, a nutrient medium 

 for the germinal substance in which alone life is inherent. 



The germinal plasm, as Weismann puts it, " never arises 

 anew but grows and reproduces itself uninterruptedly ". 



Natural philosophy poses the question: How, then, did 

 this substance arise in the first place? Weismann himself 

 only gave a very general and rather vague answer. He stated 

 that in the beginning, under special conditions which are 

 quite unknown to us, there must first have arisen very small 

 living entities, ' biophores ', which themselves represented the 

 fundamental active elements of the germ plasm." 



This idea of Weismann's was reflected in a number of 

 later pronouncements. In particular, we may take as an 

 example the * theory of symbiogenesis ' of C. Mereschkow- 

 sky," which made a great sensation in its time. According 

 to this theory there are two types of plasm which are not 

 only radically different from one another in their properties, 

 but even have a different historical origin. The first type, 

 that called ' mycoplasm ', was essentially the same as the 

 chromatin of the nucleus. The second type — called ' amoebo- 

 plasm ' — was simply what we now call cytoplasm. The very 

 earliest forms of life, which were formed spontaneously at a 

 time when there were still no organic substances and when 



