I46 Cells; or, Evolution. 



or pathogenic, like the phthisis microbe mentioned 

 above; that is to say, which are capable of devel- 

 oping disease. However alike in form, these sets 

 of organisms are different in function; and, no less 

 than the great organisms in nature, they are differ- 

 ent in species. It appears in short that there is a 

 whole series of microscopic animals, which are re- 

 lated indeed, and which are altogether alike to the 

 eye, or are more or less so; but they are in many 

 respects greatly unlike, embryologically and physio- 

 logically. " This is a region of life in which we 

 touch, as it were, the very margin of living things. 

 If nature were capricious anywhere, we might expect 

 to find her so here. If her methods were in a slov- 

 enly or only half-determined condition, we might 

 expect to find them here. But it is not so. Through 

 years of the closest observation it will be seen that 

 the vegetative and vital processes generally of the 

 very simplest and lowliest life-forms are as much 

 directed and controlled by immutable laws as the 

 most complex and elevated." This then negatively 

 and positively settles the question of spontaneous 

 generation, which we have otherwise called organic 

 evolution. 



161. That was one feat of science to discover 

 such beings as consisted only of a single 



Multicellular „ whether m the plant or animal order< 

 Organisms. ' l 



It was another achievement to unveil 

 the great fact that every organic being, no matter 

 how complex and perfect and individual in its unity 



