48 



LEAVES FROM MY NOTE-BOOK. 



Plants under Variation was published, one may conclude that the 

 small size of these rabbits results from great numbers depending 

 on a scant}' food supply. The necessity of looking out sharply for 

 themselves also accounts for the fact that the brain capacity of the 

 Porto Santo rabbits is very little less than that of the ordinary wild 

 rabbit. In this respect the large lop-eared domestic breeds rank 

 lowest ; the skull in these animals has increased in length, but with 

 a totally disproportionate weight of brain therein (see table, p. 133). 

 Darwin concludes that most naturalists, on observing these Porto 

 Santo rabbits with their reduced size, their fur, reddish above and 

 grey beneath, their tails and ears not tipped with black, and above 

 all the fact that they refused to couple with other rabbits, would 

 have ranked them as a different species. Yet these differences 

 certainly originated since the year i42o.'''' 



Dogs. 



It is well known that dogs which have relapsed into a feral 

 state lose the habit of barking, this being a faculty apparently 

 depending on the companionship of man and consequent stimu- 

 lation of the dog's emotional and rational powers. Who that has 

 been attached to a spaniel has not noticed the almost painful 

 efforts these affectionate creatures make to express more feeling 

 than can be got into a bark ? 



The Mackenzie River dogs of the Canis latrans type, when 

 brought to England, never learnt to bark properly ; but one born 

 in the Zoo " made his voice sound as loudly as any other dog of 

 the same age and size." Not only is the habit of barking quickly 

 regained by dogs which have lost that habit in the feral (relapsed) 

 state, but there is evidence that it can be acquired by both wolf 

 and jackal whelps in one generation. t 



Some dogs which had run wild on Juan de Nova in the Indian 

 Ocean, entirely lost the faculty of barking, showed no inclination 

 for the company of other dogs, and did not acquire their voice 

 during a captivity of several months. On the island they congre- 

 gate in vast packs, and catch sea-birds with as much address as 

 foxes could display. In New Guinea and Tierra del Fuego the 



* Ibid., 117 — 20, Table of skull and brain measurements, p. 113. 



t Ibid., pp. 27 — 8. 



