Sends a letter from William Huggins about a case of inherited fright in three generations of mastiffs. Discusses the different origins of instincts and their inheritance.

Recounts instances suggesting that animals have a sense of direction.

Comments on article ["Perception and instinct in lower animals", Nature 7 (1871): 377–8].

Explains his contention that "many of the most wonderful instincts have been acquired, independently of habit, through the preservation of useful variations of pre-existing instincts". Cites examples: sterile workers of several species of social insects have acquired different instincts; movements of tumbler pigeons. Speculates that "many instincts have originated from modification or variations in the brain".

"The following fact with respect to the habits of ants, which I believe to be quite new, has been sent to me by a distinguished geologist, Mr J. D. Hague [see 8788]; and it appears well worth publishing."

Sends a letter from J. D. Hague confirming his earlier observation [see 8788] of frightened behaviour of ants when they come upon dead ants. CD had asked for confirmation because J. T. Moggridge had suggested that the ants’ behaviour was alarm at the scent of the observer’s fingers.

CD, in commenting on Wyville Thomson’s "Notes from the Challenger" [Nature 8 (1873): 347–9], recapitulates his work on rudimentary male cirripedes [Living Cirripedia], especially the complementary males attached to hermaphrodites. Offers an explanation, on evolutionary grounds, of their function and size.

Sends, with CD’s approval, a clarification of CD’s explanation of how useless organs might diminish [see 9061]. Using Quetelet’s law of normal distribution GHD shows how horns of cattle, having become useless, would gradually diminish and finally disappear.