428 BIOGRAPHICAL SKETCHES. 
1844, being a part of the manuscript of a chapter in his 
“Origin of Species;” also of a private letter addressed to 
the writer of this memorial in October, 1857, — the publica- 
tion of which (in the Journal of the Proceedings of the Lin- 
nean Society, Zodlogical Part, iii. 45-53, issued in the sum- 
mer of 1858) was caused by the reception by Darwin himself 
of a letter from Mr. Wallace, inclosing a brief and strikingly 
similar essay on the same subject, entitled “On the Tendency 
of Varieties to depart indefinitely from the Original Type.” 
Mr. Darwin’s action upon the reception of this rival essay 
was characteristic. His own work was not yet ready, and the 
fact that it had been for years in preparation was known only 
to the persons above mentioned. He proposed to have the 
paper of Mr. Wallace (who was then in the Moluccas) pub- 
lished at once, in anticipation of his own leisurely prepared 
volume ; and it was only under the solicitation of his friends 
cognizant of the case that his own early sketch and the cor- 
roboratory letter were printed along with it. 
The precursory essays of Darwin and Wallace, published 
in the Proceedings of a scientific society, can hardly have been 
read except by a narrow circle of naturalists. Most thought- 
ful investigating naturalists were then in a measure prepared 
for them. But toward the close of the following year (in the 
autumn of 1859) appeared the volume “On the Origin of 
Species by means of Natural Selection, or the Preservation of 
Favored Races in the Struggle for Life,” the first and most 
notable of that series of duodecimos which have been read 
and discussed in almost every cultured language, and which 
within the lifetime of their author have changed the face and 
in some respect the character of natural history, — indeed 
have almost as deeply affected many other lines of investiga- 
tion and thought. 
In this Academy, where the rise and progress of Darwinian 
evolution have been attentively marked and its bearings criti- 
cally discussed, and at this date, when the derivative origin of 
animal and tegetable species is the accepted belief of all of us 
who study them, it would be superfluous to give any explana- 
tory account of these now familiar writings; nor, indeed, 
