skip to content

Darwin Correspondence Project

To Louis Agassiz   19 August 1868

Down Bromley | Kent [Freshwater]

Aug 19. 1868

C. Darwin

Dear Sir

I thank you cordially for your very kind letter.1

I certainly thought that you had formed so low an opinion of my scientific work that it might have appeared indelicate in me to have asked for information from you, but it never occurred to me that my letter wd have been shewn to you.2 I have never for a moment doubted your kindness & generosity, & I hope you will not think it presumptuous in me to say that when we met many years ago at the Brit. Assoc. at Southampton I felt for you the warmest admiration.3

Your information on the Amazonian fishes has interested me extremely, & tells me exactly what I wanted to know. I was aware, through notes given me by Dr Günther, that many fishes differed sexually in colour & other characters,4 but I was particularly anxious to learn how far this was the case with those fishes, in which the male, differently from what occurs with most birds, takes the largest share in the care of the ova & young.

Your letter has not only interested me much, but has greatly gratified me in other respects, & I return you my sincere thanks for your kindness.

Pray believe me my dear Sir | yours very faithfully | Charles Darwin


The annual meeting of the British Association for the Advancement of Science took place in Southampton in 1846; CD was vice-president of the botany and zoology section, and Agassiz delivered a paper on the fishes of the London clay (Report of the 16th meeting of the British Association for the Advancement of Science held at Southampton in 1846, p. xv; Transactions of the sections, p. 52).


Thanks LA for information on sexual differences in the coloration of Amazonian fish. CD was anxious to know how the sexes differed because they are unusual in that the male has the largest share in looking after ova and young.

Letter details

Letter no.
Charles Robert Darwin
Jean Louis Rodolphe (Louis) Agassiz
Sent from
Freshwater Down letterhead
Source of text
Houghton Library, Harvard University (MS Am 1419: 278)
Physical description
LS 4pp

Please cite as

Darwin Correspondence Project, “Letter no. 6323,” accessed on 10 December 2022,

Also published in The Correspondence of Charles Darwin, vol. 16