TEANSACTIONS OF SECTION D. 211 



flowered Composites {Hyijochceris, &c.), on which they are fre- 

 quently to be seen. The same is apparently true of the many 

 flower-visiting genera of Diptera, especially Syrphus, which 

 find in our introduced flowers a very abundant food-supply. 



The disappearance of native birds is probably due more 

 directly to man than to the animals he has introduced. Ex- 

 ception must, however, be made with regard to the animals of 

 the weasel kind, which are of very recent introduction. Many 

 of the larger birds, formerly common, have completely disap- 

 peared from the settled districts, having been shot for food by 

 the earlier settlers. Many still survive to find an increased 

 food-supply. Thus, tuis and korimakos are still common in 

 gardens and orchards, finding abundance of nectar in fruit- 

 trees, blue-gums, fuchsias, and other introduced flowers. 

 Parrakeets are very destructive to fruit-gardens and grain- 

 crops ; and, in the neighbourhood of bush districts, kakas are 

 fond of raiding the corn both in the stook and after it is 

 stacked. The increase of the rabbits in many parts led to a 

 great increase in the numbers of wekas, which were able 

 to attack and destroy the young ones. Phosphorus, and 

 especially ferrets, have, however, nearly exterminated them 

 within the last few years. 



The time which has elapsed since the earliest immigration 

 of European forms may be considered too short to have al- 

 lowed any marked variations of plants and animals to have 

 arisen. Thirty years ago, Darwin, and those who embraced 

 his views, called in the aid of vast periods of time in which to 

 allow variation to reach specific value. But the accumulated 

 experiences of the intervening period since the publication of 

 the "Origin of Species" show, from the results obtained by 

 breeders of animals and producers of new strains of plants, 

 how very rapidly and in how few generations difierences 

 arise which, were we to find them in a state of nature, would 

 be considered to be of specific, if not, indeed, of generic 

 importance. 



When once a favourable variation or, as in some of the 

 cases cited, an unsuppressed variation arises, it frequently is 

 reproduced with great rapidity. I have one or two singular 

 instances among domestic animals which show this fact, but 

 shall only advance the following case, which is an interesting 

 one : — 



In the district of Strath-Taieri, in Otago, some years ago, 

 certain sheep on one of the runs — probably the progeny of a 

 single ram — were found to be evidently short-winded. Ap- 

 parently the action of the heart was defective, for when these 

 sheep were driven they would run with the rest of the flock 

 for a short distance, and then lie down panting. The result of 

 this peculiar affection was that, at nearly every mustering, 



