270 E.VOLUTION OF TO-DAY. 



parent, are points yet in dispute. More important 

 still is the question whether an animal is able to in- 

 herit from its parents any features newly acquired by 

 them, i. e., any peculiarity which its parents ac- 

 quired after reaching their adult condition, such as 

 accidental mutilations, etc. These variations are 

 known as acquired variations, and it is still a ques- 

 tion not definitely settled how far they can be trans- 

 mitted from one generation to another. It might 

 seem that these points wonld be easy enough to 

 settle by simple observation, and doubtless every 

 one will call to mind instances which seem to prove 

 the truth of some of these positions. But so many 

 modifying circumstances arise to vitiate the results, 

 and so contradictory are the various facts observed, 

 that it has been found thus far impossible to come 

 to any unanimous conclusion even on these simple 

 questions of fact. 



The first hypothesis which we notice is that of 

 the German naturalist Weismann. This we con- 

 sider first, not because it is the oldest, for it is the 

 most recent theory ; but because it is the simplest, 

 and has a direct bearing upon the theories of evolu- 

 tion. In his explanation Weismann turns for assist- 

 ance to the lowest animals and plants the unicel- 

 lular organisms, in which reproduction is the simple 

 result of growth. In these animals the amoeba, 

 for instance the body consists of a small bit of 

 protoplasm, without much differentiation into parts. 

 Having no mouth nor respiratory organs, they must 

 absorb all of their food and gases through the sur- 

 face of the body. Now, by a well-known mathe- 



