T-ECTURE XVI. 461 



fundamental differences cannot^ in my opinion be reasoned 

 away, nor can I comprehend tlieir development from one ori- 

 ginal form. What I can understand is this, that each of the 

 plans may, in its increasing simplification, be traced back to an 

 ideal original form of organic development — ^the cell ; and, as 

 I have already observed, it appears to me very probable that 

 the elementary cells have from the beginning been differently 

 constituted, which differentiation is manifested in the develop- 

 ment of the fundamentally different structural plan, which is 

 recognised in the animal kingdom. I repeat, I am far from 

 adopting either a formal original substance or one cell form as 

 the fundamental type and beginning of the whole organic crea- 

 tion. As I find in the present creation animals and plants con- 

 sisting of a single cell, which present a different composition, 

 different forms, and a different mode of life and of propagation, 

 I do not see why the primary single-celled organisms which 

 might have arisen from the elementary substances should all 

 have possessed the same formj quality, and capacity for 

 development. 



It is sufficient for me to have shewn that an original diffe- 

 rence may exist by the side of modification and adaptation, 

 that both must supplement each other in order to render intel- 

 ligible the picture presented by organic nature. 



Let us after this digression return to our theme, the origin 

 of man and his descent from the ape. 



The course of lectures which I conclude this day, had for its 

 object the indication of the kind of studies requisite in order to 

 arrive at certain results. I have endeavoured to show in what 

 respects the organisation of man differs or agrees with that of 

 the ape. I endeavoured to indicate the fundamental plan in 

 the structure of the individual organs, which is evidently the 

 same in man and ape. But whilst insisting on the identity of 

 the plan, I pointed out the difference in its execution, in the 

 same manner as a teacher of architecture may demonstrate the 

 unity of the plan in several Grothic cathedrals, whilst at the same 

 time he points out the diversity of its execution in the respective 

 minsters. I have proved to you that the differences between some 

 human races are greater than those subsisting between some ape 



