204: EEPOET— 1891. 



hitherto, and which even in some cases are not visited by 

 these insects in their native countries. This is just one of 

 those points in connection with naturahsation which want 

 careful and continued observation, and from which we can see 

 how mutually dependent on one another are the various organ- 

 isms concerned. As an example, I would suggest the following 

 case : Prwiula clatior and Primula veris, the parent forms of 

 our common garden polyanthus, are both lieterostyled species. 

 If humble-bees visit these flowers for pollen, which is all that 

 I have seen them doing, — the nectar being beyond the reach of 

 their trunks, — only the short-styled flowers will be visited, as 

 in them the anthers are placed at the mouth of the corolla- 

 tube. According to Hernaann Miiller, humble-bees (in Europe) 

 learn to recognise the long-styled flowers at a distance and 

 avoid them, and if they do visit them they only accomplish 

 self- and not cross-fertilisation. It is more than probable, 

 then, that, by persistent fertilisation of one kind of flower only, 

 a change of form — or, at least, some change in the lietero- 

 styled character ^ — may gradually arise in these introduced 

 Primulas. 



(c.) Some Changes undergone by or in Process of 

 Occurrence among Introduced Animals. 

 One of the most interesting points connected with the 

 successful naturalisation of foreign species is the observation 

 of the changes which they undergo under tlieir altered con- 

 ditions. Nearly all our introduced animals have been brought 

 from lands where the struggle for existence is very keen and 

 where natural enemies abound. In their new home they have 

 been set free from these old trammels, and their enemies have 

 been left behind. Under such circumstances it is not surpris- 

 ing to find that sports in colour, which in Europe would be 

 strictly eliminated as soon as they appeared, owing to their 

 rendering their possessors too conspicuous to their enemies, are 

 here preserved and tend to be reproduced. This is particularly 

 noticeable among rabbits. In the neighbourhood of towns and 

 villages, w^here cats, dogs, and sportsmen abound, the sober 

 greys and browns of the wild rabbit are the colours commonly 

 seen ; but in the country districts, away from all enemies 

 except professional rabbiters and phosphorized oats, neither of 

 which are likely to exert much selective action on their colour, 

 it is as common to see black, white, yellow, and piebald rabbits 

 as the ordinary greys. The same remark applies, but in a less 

 degree, to our introduced birds. Among house-sparrows in 

 particular, variation in colour and especially development of 

 white feathers is extremely common, and is certainly on the 

 increase. From evidence I have collected in Otago, I find 

 that the development of white plumage, usuallj' in the wings 



