GENERAL INTEODUCTION. Ixsxix 



surroundings would have resulted in the forn^ation of 

 perfect germ-cells. 



I had some hope that this hybrid would be fertile, for 

 in its breeding it agreed with a hybrid (referred to by 

 Darwin and others) which is said to have had offspring 

 when mated with a pony. In the ' Gleanings from the 

 Knowsley Menagerie ' there is a figure (lix, 2) of this 

 triple hybrid, and at p. 73 it is described as follows : — 

 " The offspring of a mule (the produce of a male ass a,nd 

 a zebra) with a bay mare pony. Iron-grey with a short 

 narrow cross-band on withers ; very faint indications of 

 stripes on the sides, and more distinct dark stri^oes on 

 outside of the hocks and knees ; tail bushy from the base 

 like a horse, head heavy, mane brown and grey. This 

 animal used to di'aw a small cart. It stands eight hands 

 high.''' Darwin, writing in the seventies, says of this 

 cross, " Many years ago I saw in the Zoological Gardens 

 a curious triple hybrid from a bay mare by a hybrid from 

 a male ass and a female zebra." 



Not a few mistakes have been made about hybrids. 

 There is, for example, the famous case of the fictitious 

 cross between the hare and the rabbit, and one occasion- 

 ally hears of a hybrid, equally improbable, between a dog 

 and a fox. Yet it is not likely Darwin would make so 

 pointed a reference to this triple hybrid had he not 

 satisfied himself that it was genuine. An effort is being 

 made in the gardens of the Melbourne Zoological Society 

 to induce a zebra-ass hybrid to breed. This hybrid is 

 certainly now old enough, and, with its genial climate, 

 Melbourne seems peculiarly well adapted for an experi- 

 ment of this kind. It need hardly be urged that the first 

 possible opportunity that offers should be taken to examine 

 the male germ-cells of ordinary mules and hinnies. This 

 could be best done where mules are common, and where 

 specimens of various ages are available. 



Sterility of Female Zehra Hyhrids. — Periodically it is 

 asserted in the Field, or in some other newspaper, that a 

 female mule has produced a foal. Sometimes the inter- 

 esting event is said to have taken place in the East, 



9 



