EVOLUTIONS OF ORGANIZATION. iy 



warned him from adhesion to spontaneous gener- 

 ation. But I hold him to be right in considering 

 the progress from simpler to more complex life in 

 the history of the earth as being analogous to the 

 development of an individual from the embryonic 

 to the adult condition, a definite, and not an inde- 

 finite evolution. 



Such were the various views involving an evol- 

 ution in one sense or another with which biology 

 was familiar before the year 1859, when Darwin's 

 Origin of Species made its appearance. In that 

 work there is full agreement with Lamarck in res- 

 pect that the origin of life from a creator is frankly 

 and continually referred to, and that the question 

 brought up is essentially the old one of the degree 

 in which forms through long epochs of time are 

 capable of changing ; but spontaneous generation 

 is let alone, and the author is content to express 

 his belief that "animals have descended from at 

 most only four or five progenitors, and plants from 

 an equal or lesser number." l The new element 

 imported into the discussion is, as you are aware, 

 what he terms " natural selection," -a result of the 

 struggle for existence. This struggle for existence 

 had already been pointed out by Owen 2 as a potent 



1 Origin of Species, 3rd edition, p. 518. 



2 Zoological Transactions, vol iv, p. 15. See, also, Comparative Anat- 

 omy of Vertebrates, vol. iii, p. 799. 



B 



