414 LECTUSE XIV. 



frequently eflPected by the interference of man, wlien generally 

 some tricks are required to deceive the male and so to conquer 

 its aversion to a female of a different species. The stallion 

 who is to cover a she-ass is frequently first excited by the pre- 

 sence of a mare, for vs^hich at the proper moment the she-ass 

 is substituted. The same manoeuvre is often resorted to, to 

 induce thorough-bred staUions to cover plough horses. They 

 frequently refuse, until one of their favourite mares is pro- 

 duced, after which they are deceived in the above manner. 

 But though in common cases, the interference of man is requi- 

 site for the production of hybrids on a larger scale, there are 

 a sufiicient number of cases known of the occurrence of hybrid- 

 ity in a wild or semi-wild state. Dog and she-wolf, fox and 

 bitch, dog and jackal, ibex and goat are authenticated instances 

 of this kind. 



The hybrids present in the average a mixture of the physical 

 and mental characters of the parents. There persists, how- 

 ever, a certain individuality, as the intermixture does not affect 

 the separate organs in equal proportions. The description of 

 wolf-dogs as given by Buffon, shows very clearly how far this 

 difference may extend to the young of a single Htter. 



Whilst thus the production of bastards with characters 

 equally remote from those of both parents may take place with 

 or without the interference of man, the question whether inter- 

 mediate species may arise is not thereby solved. It is not 

 merely requisite that the hybrids should be able to inter- 

 breed, but that their progeny should be prolific so that the 

 species may be continued ; for, unless this were the case, the 

 new species would become extinct. Supposing that the hybrids 

 are not prolific between themselves, but are so with the parent 

 stock, the hybrid character would, after a few generations, 

 become again obliterated. Let us suppose a wolf-dog, half- 

 wolf, half-dog, covering a bitch. The offspring is now only 

 one-foui'th wolf and three-fourth dog, and if this three-quarter 

 dog and his progeny are crossed with bitches, the quantity of 

 wolf-blood must finally be so miich reduced as to be no longer 

 perceptible. Traces of such an intermixture will now and 

 then appear in some of the descendants, which, perhaps, may 



