White. — On Hybridism. 199 



most or all of the AnatidcB become " flappers " in the early 

 autumn, owing to the loss of the pen-feathers. In New Zea- 

 land the paradise-duck (Casarca variegata) and the mountain 

 blue-duck (Hymenolemus ?nalacorhynchus'?) I have seen as flap- 

 pers, but they undergo no change in colour during that period. 

 But I have no recollection of ever seeing the mature grey-duck 

 (Anas superciliosa) without flight-feathers, but this might be 

 owing to their retirement to large water areas. If a duck is 

 sitting on a second hatching of eggs the time of moulting is 

 deferred, which is a singular instance of adaptation to circum- 

 stances. 



Aet. XXI. — On Hybridism. 

 By Taylor White. 



[Read before the Hawke's Bay Philosophical Institute, 26th October, 



1900.] 



The study of hybridism, when such can be systematically 

 and successfully followed out, will no doubt be one of the 

 great factors whereby we shall in a great measure obtain a 

 more correct insight into the secrets of creation and the origin 

 of species. By inference we can conclude that all vegetable 

 and animal life having kindred affinities has descended to our 

 time along the one ancestral line. Take the ruminants, for 

 instance, whose internal conformation is so arranged that 

 they are fitted to chew the cud, and so are enabled to 

 hurriedly collect food-materials with which they retire to a 

 secluded or favourite "camp," where they contentedly put it 

 all through the mill a second time : it is not possible for us of 

 the present time to hold any theory admitting of a separately 

 distinct creation of all the many species of ruminants; rather 

 we assume they are all descended along the branches of the 

 one ancestral tree. Admitting such descent along the same 

 ancestral line, we are confronted by these problems : Why do 

 closely allied species not breed together in a state of nature? 

 At what stage did they lose the sexual instinct between a 

 newly formed species and that from which it had imme- 

 diately descended? Was it necessary for either species to 

 be geographically divided? W T hat influence — atmospheric, 

 geographic, or otherwise — caused species to differentiate, and 

 why do we now find all species stable, and incapable ol ' 

 throwing off a further distinct species ? 



At the present time species may vary within certain limits 

 only — for instance, among the domestic sheep we find many 



