272 Dr Morton on Hybrid Animals and Plants, 



The greatest number of mammae in the common dog is ten, 

 the smallest number, six ; in the wild species they are always 

 in pairs, and they never vary in a species. " To what other 

 cause, then, can we ascribe the anomaly in domestic dogs, so 

 justly as to an intermixture of species ^"* 



The dogs that have become wild in Paraguay, always hunt 

 in packs, thus resuming the wolf-life instinct of their proge- 

 nitors. Will it be said that this is a newly developed in- 

 stinct \ or is it not rather an old one that new wants have re- 

 produced. 



It is therefore certain that dissimilar species of the dog 

 tribe are capable of producing a fertile hybrid offspring ; and 

 if it was the interest of man again to cultivate and extend 

 these mixed species, there is every probability that the race 

 would become unlimited. 



" Experiments shew," observes Mr Lyell, *• that after re- 

 peated failures, the union of two recognized species may at 

 last, under very favourable circumstances, give birth to fer- 

 tile progeny ; and such circumstances," he adds, " the na- 

 turalist may conceive to have occurred again and again in 

 the course of a great lapse of ages."t 



Every one who is in the least degree acquainted with the 

 natural history of dogs, knows that certain remarkable 

 changes of colour, and sometimes of form, take place in par- 

 ticular localities. These changes are usually attributed 

 solely to climate, food, training, and other exterior agents. 

 I do not deny the modifying action of such agents in these 

 and other cases ; but it is a reasonable subject of inquiry , 

 whether there may not be something in these localities that 

 favours an effort of nature to reproduce a primitive type ? 

 The localities to which we allude,J do not operate equally 

 on all varieties of the dog tribe ; which we might suppose 

 would be the case if all the canine breeds were derived from 

 a single stock or species. It is important, in connection with 

 this subject, to observe that all the pure Indian dogs of 



* Nat. Hist, of the Dog, in Nat. Lib., vol. ii., p. 79. 

 t Principles of Geology, Book III., chap. 2. 



\ See Dr Prichard's Natural History of Man, for an admirable exposition of 

 these and all other facts on which the analogical avjumcnt is founded. 



