162 THEORIES. 



thus stated : " The idea which I form of the pro- 

 gress of organic life upon our earth, and the hypo- 

 thesis is applicable to all similar theatres of vital 

 being, is, that the simplest and most primitive 

 type, under a law to which that of like productions 

 is subordinate, gave birth to the type next above 

 it ; that this organ produced the next higher, and 

 so on to the very highest, the stages of advance 

 being in all cases very small, namely, from one 

 species only to another ; so that the phenomenon 

 has always been of a simple and modest character." 



This theory assumes that the monad we have 

 already considered, the simplest form of animal 

 life, was first created ; that it gave birth to the 

 next species of animalcules, and that onward this 

 development proceeded, till the animalcule was lost 

 in the mollusk, and the mollusk in the monkey, and 

 the monkey in the man ! 



Now it ought to have been enough for the 

 holders of this theory to have set themselves to 

 answer the question, if such a power of develop- 

 ment were possessed by cells, how has it become 

 extinct ? Innumerable facts attest that the monad 

 produces only monads, and that throughout organic 

 nature the germ is precisely like its parent. No 

 species trespasses on the boundary line of another 

 species. In its development, the Divine voice may 

 be heard, saying : " Hitherto shalt thou come, but 

 no further." And the declaration may not only be 

 substantiated by the observations of every passing 



