THE GERM-PLASM THEORY 71 



Clarendon Press collection of Weismann's papers. 

 Here it need only be said that belief in the trans- 

 missibility of mutilations has now disappeared 

 from scientific minds. 



As regards the inheritance of other acquired 

 conditions, Weismann was at first supposed to 

 deny that the environment could produce any 

 effect upon the included germs and therefore 

 upon the individuals into which they might 

 develop. We say " supposed," for this was gener- 

 ally taken to be his meaning, though, in the work 

 now under consideration, he states that this view 

 was a misunderstanding of his position, and com- 

 plains (ii. 195) that he has " been frequently and 

 persistently credited with maintaining that the 

 germ-plasm is invariable." In any case, as will 

 shortly oe seen, he only allows that the environ- 

 ment can operate in a very roundabout manner 

 upon ths germ-plasm. But what is this germ- 

 plasm, and what, according to Weismann, are its 

 characters ? In order to explain this one must 

 first consider the condition of a unicellular organ- 

 ism. Hers we have an individual in which all 

 functions, respiration, digestion and the like, take 

 place in the same cell. When multiplication is to 

 occur, the cell divides into two, each becoming a 

 new and separate individual, neither of which can 

 be spoken of as mother or as child. It is clear that 

 such an individual can be killed by deprivation 

 of moisture or by other means ; but, given suitable 

 conditions, there is no reason why such a form 

 should ever die ; it is potentially immortal. 



The first stage in the direction of complexity 



