GENERATION, SEX AND ONTOGENY 



215 



often 1)e mot with in the writings of Weismann and certain other 

 modern philosophical biologists. There is a fallacy, however, 

 in the phrasing, because, 

 as a matter of fact, the 

 protoplasm of a given 

 protozoon gradually loses 

 its vitality with con- 

 tinued division until it 

 ultimately is unable to 

 divide further or indeed 

 to perform the other life 

 functions: it dies of old 

 age. 



Hardly less simple is 

 generation by budding, 

 which in its simplest 

 character is the breaking 

 off from one individual 

 of a part smaller than a 

 half, often, indeed, only 

 a vory small fractional part, which 

 capacity of growing and developing 



FIG. 121. Stentor reproducing by fission. 

 (After Stein.) 



budded off part has the 

 into a new individual like 

 its parent. 



A still other 

 mode of generation 

 of simple type is 

 that of sporulation, 

 or where the body 

 of one individual 

 subdivides into 

 more than two 

 parts (as in binary 

 fission), these parts, 

 each of which is 

 usually subspherical 



I ;. \'22.~IIolophrya multifiliis, an infusorian parasitic 

 on fishes reproducing by sporulation. 



Or ellipsoidal, 

 bering perhaps 



many hundreds. 



A condition known as parthenogenesis is found among 

 rrrtain of the complex animals. Although the species is repre- 

 sented by individuals of both sexes ; the female can produce 



