MEMOIR. XXXVII 
In January 1861 Bates married a young lady for whom he 
had kept a tender place in his heart during his long absence— 
Miss Sarah Ann Mason, of Leicester, by whom he had three 
sons and two daughters. Darwin writes to congratulate him and 
to hope that he “may succeed, for the sake of science, in getting 
fixed near London.” Meanwhile, he was hard at work over his 
book, writing and re-writing the earlier chapters—some of them 
being recast three and four times before his severe judgment 
was satisfied. “What takes me one day to write takes five to 
alter,” he says in one of hisletters. Darwin, who generously spared 
time to read the manuscript, writes under date January 13th, 
1861 :— 
‘‘T have been very bad for a fortnight, and could not read your MS. before 
to-day and yesterday. It is, in my opinion, excellent—style perfect, descrip- 
tion first-rate (I quite enjoyed rambling in forests), and good dashes of 
original reflexions. . . . I feel assured that your book will be a permanently 
good one, and that your friends will always feel a satisfaction at its publica- 
tion. I will write when you like to Murray.’’ 
Concurrently with this, Bates wrote his celebrated paper on 
“Mimicry,’ * which is his distinctive contribution to the theory of 
natural selection. The observations which led him to the ex- 
planation of those curious phenomena known as “mimetic analogies” 
were made upon insects, which group supplies by far the larger 
mass of evidence. 
In looking for hints of these observations during his travels, 
one is found in a letter from St. Paulo, September 5th, 1858, 
printed in the Zoologzst, vol. xvi., pp. 6165-6 :— 
‘In the shady ravines of the forest, many species of Ithomiz were found 
in greater or less abundance. . . . Flying amongst the Ithomiz was now and 
then to be observed a Leptalis; I was very careful to secure every specimen. 
and the gathered series, now I come to examine them closely, have interested 
me as much as any other acquisition made during my excursion. Abstraction 
made of a white species and the Vocula, the rest may be considered either as 
six species allied to L. Lysinoé (fewz¢s.), or as the latter branching out into 
six rather widely differing varieties. In either case they are very interesting, 
because some of the kinds come to imitate each a species of Ithomia, 
common only in this locality. It would seem then almost correct to say that 
at Ega and other stations these new Leptales are not found, because the 
{[thomia to which they correspond are also absent. L. Lysinoé imitates 
Ithomia Flora; but three at least of the new species imitate three of the 
* This term has been chosen by biologists merely for convenience, and not as implying 
conscious or voluntary imitation on the part of the mimicking species, 
