…so don’t expect him to hold your hand while you mouth the words you’re trying to read out of his tome. If he feels like quoting somebody in French and you don’t know the difference between salut and adieu, well, tant pis pour toi!
But seriously, he quotes various people in the original French, some of it important and thorough technical information, and he never translates a word for the reader. Just assumes you can read it or will work it out if you care. The picture is the fourth instance, at least, in Descent of Man, and it’s by far the shortest and simplest quote. The first of the book proper (there’s one in the introduction, too) appears on page four of my edition and reads as follows:
“It is notorious that man is constructed on the same general type or model as other mammals. … Vulpian remarks: Les différences feelles qui existent entre l’encéphale de l’homme et celui des singes supérieurs, sont biens minimes. Il ne faut pas se faire d’illusions à cet égard. L’homme est bien plus près des singes anthropomorphes par les caractères anatomiques de son cerveau que ceux-ci ne le sout non-seulement des autres mammifères, mais même de certains quadrumanes, des guenons et des macaques. But it would be superfluous here to give further details…”
I speak a little French, but I’m missing a bit of this, too — I think feelles, at any rate, is antiquated language if it’s not a typo. The gist of the long quote is that the differences between the human brain and that of the anthropomorphous apes is very small, much smaller than the differences between the higher and lower primates. The author quoted says we should not delude ourselves about this. (Side note: sad, isn’t it, that some still insist on deluding themselves about such things more than 140 years after Darwin was quoting somebody else who already had said this.)
The handwritten quote in the image says that it’s dangerous, in the sciences, to make hasty conclusions. Same’s true outside of science, of course–first lesson of philosophy, for one.