MANY OR ONE ANCESTRAL STOCKS ? '45 



to trace the first origin of all individual groups of organisms, 

 as well as their totality, to a single common species of 

 Moneron which originated by spontaneous generation (vol. i. 

 p. 343). The multiple, or polyjiliyletic, hypothesis of descent, 

 on the other hand, will assume that several different species 

 of Monera have arisen by spontaneous generation, and that 

 these gave rise to several different main classes (tribes, or 

 phyla) (vol. i. p. 3-i8). The apparently great contrast between 

 these two hypotheses is in reality of very little importance. 

 For both the monophyletic and the polyphyletic hypothesis of 

 descent must necessarily go back to the Monera as the most 

 ancient root of the one or of the many organic tribes. But 

 as the whole body of a Moneron consists only of a simple, 

 formless mass, without component particles, made up of a 

 single albuminous combination of carbon, it follows that the 

 differences of the different Monera can only be of a chemical 

 nature, and can only consist in a different atomic com- 

 position of that mucous albuminous combination. But 

 these subtle and comphcated differences of mixture of the 

 infinitely manifold combinations of albumen are not appre- 

 ciable by the rude and imperfect means of human observation, 

 and are, consequently, at present of no further interest to 

 the task we have in hand. 



Tlie question of the monophyletic or poly]3hyletic origin 

 vnll constantly recur within each individual tribe, where 

 the origin of a smaller or of a larger group is discussed. In 

 the vegetable kingdom, for example, some botanists wiU be 

 inclined to derive all flowering plants from a single form of 

 fern, while others will prefer the idea that several different 

 groups of Phanerogama have sprung from several different 

 groups of ferns. In like manner, in the animal kingdom, 



