THEORIES AS TO THE ORIGIN OF LIFE. 85 



time by an organic process actually dependent 

 on, and directly derived from, a true sexual 

 union ; out of which union sprang the first larval 

 form in the complicated cycle of changes. Thus 

 a pair of Aphides may produce, compatibly 

 with this view, a larval progeny that is fruitful 

 without any new sexual union, and this may go 

 on, time after time, till out of one union spring 

 a progeny amounting to millions of millions. 

 Still, this cycle of transformed vitality has its 

 termination ; and it ends inevitably with a 

 brood of perfect animals, male and female, of 

 identical species ivith the two out of ivhich the 

 cycle was set in its complicated movement. . . It 

 matters not whether, in speaking of the marvel- 

 lous transformations in the larval forms of any 

 given species, we tell of Parthenogenesis with 

 Owen, or of Ammen or ivet-nurses with Steen- 

 strup. Each set of phenomena is in a true 

 organic cycle, and the perfect animal, with 

 which the cycle ends, is but a repetition of the 

 same species with which the cycle started. To 

 this rule there seems to be no exception ; and 

 the theory of transmutation from one perfect 

 species to another, derives no support from mo- 

 dern Microscopic observations carried on with 



