Dear Sir.

I have read with interest D^r Huggins’s letter with your introduction to it in “Nature”.¹ Is it not just possible that in all the cases mentioned a nervous temperament in this family of dogs was suddenly and painfully excited by the smell of meat; just as some persons are excited by the smell of cheese: leaving only the temperament to be inherited. Mr Wallace makes in his letter of this week to “Nature” a most ingenious hypothesis for the “homing” faculty in Animals²—basing it on association through the sense of smell—but as long as we do not know that this sense is so used, is it not more probable that the animals taken from home blindfold had had some previous experimental knowledge of the country passed over, though, through inattention to their habits, we have not observed the means by which they acquired it?

I cannot get a good case of “homing” where the following conditions have been undoubtedly fulfilled. 1. That the animal is known certainly to have had no opportunity, either alone or with some person, of acquiring any knowledge of the road. 2. That the return has been effected within such a time as the animal would ordinarily have occupied in travelling the distance. People let their dogs wander about the country on their own business until nearly full grown. (I know that they travel many miles on their own account) then give them away to some person, say 20 miles off, and are astonished(!) to see the animals come back in a few days (not hours) emaciated and dirty and with their nails worn down to the quick. In fact just as they have been poking about like a man in the dark to find a landmark. But a little touching up perhaps sends the story into a respectable journal, deprived of all the data by which we can recognize its true significance. A case occurred lately in this house which looked like an undoubted case of “homing” and I allowed many persons to think so; and no one in the world besides myself happened to have seen how the experimental knowledge was gained. I have published my account of the case with the explanation and others have published it without.³

I cannot satisfy myself of a single instance where conditions 1 and. 2 have been fulfilled and until then I must believe that these cases no more show instinct than does the “homing” of the pigeon.

With apologies for troubling you I am, Dear Sir, yours faithfully Arthur Nicols.

To | Charles Darwin— Esq. FRS etc