The Origin of Organic Forms. 1 89 



highly organized. Over the whole region open to 

 observation, the lowest organisms are as fixed as the 

 highest : they are never modified to such an extent as 

 to change their kind. To draw out a genealogical tree 

 of the totality of species, it would be necessary to find 

 a series of organisms that have passed by direct ascent 

 into more highly organized species. But just as 

 science looks in vain for the common ancestor of man 

 and the monkey, so does it search to no effect for the 

 common ancestor in every case of diffentiated species 

 down to the simplest. The discovery of forms assimi- 

 lated to allied species on either side, and in part 

 filling up the interval between, will not furnish satis- 

 factory evidence of the transition, unless there is proof 

 that the allied species are its offspring. What is 

 wanted is the immediately precedent organism out of 

 which the more advanced has sprung. Such common 

 parentage is nowhere found. The very thing needed 

 to give an unassailable basis for the hypothesis of 

 organic evolution is, from the lowest point to the 

 highest, along the whole line, invariably and entirely 

 absent: the genealogical tree is altogether made up 

 of branches ; it has no stem. 



The series embraced in organic evolution includes 

 Man. The proposal to treat him as an exception is 

 fore-doomed. It is a half-way house, which cannot 

 be the permanent home of science. Every argument 

 against the inclusion of the human organism in the 

 evolution process has its* counterpart equally effective 



