244 



DARWIN. 



in the Journal of 'the Linncean Society, June 30, 1858, 

 the first consisting of an abstract of Darwin's manu- 

 scripts of 1839 and 1844, from the second part, 

 entitled " On the Variation of Organic Beings in a 

 State of Nature; on the Natural Means of Selec- 

 tion ; on the Comparison of Domestic Races and 

 True Species"; also the letter of 1857 to Asa 

 Gray. The second consisted of the paper by Wal- 

 lace, written in February, 1858, entitled " On the 

 Tendency of Varieties to depart indefinitely from 

 the Original Type." 



The line of thought in these two papers is almost 

 directly parallel, as shown in these columns: 



DARWIN. 



There is in Nature a struggle 

 for existence, as shown by Mal- 

 thus and De Candolle. 



Rapid multiplication, if un- 

 checked, even of slow-breeding 

 animals like the elephant . . . 



Great changes in the environ- 

 ment occur. 



It has been shown in a foi'mer 

 part of this work that such changes 

 of external conditions would, from 

 their acting upon the reproductive 

 system, probably cause the or- 

 ganization ... to become plastic. 



Can it be doubted that . . . 

 any minute variation in struct- 

 ure, habits, or instincts, adapting 

 that individual better to the new 

 conditions, would tell upon its 

 vigour and health ? 



WALLACE. 



The life of wild animals is a 

 struggle for existence ... in which 

 the weakest and least perfect must 

 always succumb. 



Even the least prolific of ani- 

 mals would increase rapidly if 

 unchecked. 



A change in the environment 

 may occur. 



(No cause of variation as- 

 signed.) 



Varieties do frequently occur 

 spontaneously. 



All variations from the typical 

 form have some definite effect, 

 however slight, on the habits or 

 capacities of the individuals. 

 Abundance or rarity of a species 

 is dependent on its more or less 



