v°i-vin.1 Reviews. 47 



1908 J T^/ 



factors (temperature, humidity, and light), both in the ontogenetic 

 and phylogenetic history of the various organisms. Of the 

 various externally exerted stimuli we know little. 



As an example of dichromatism Mr. Beebe quotes our Sterco- 

 rarius. In the northern hemisphere, where the small Skuas 

 breed, it is very common to find a parti-coloured bird mated 

 with one wholly dark. Confined to Australia, a good example 

 is the GyninorJiina on land and the Reef-Heron on water. A 

 case is quoted of a parallel case of a Heron in the waters of the 

 United States of America, where parti-coloured birds are not 

 uncommon. On p. 15 Mr. Beebe says : — "While it is impossible 

 to correlate with more certainty the foregoing examples of 

 melanism and dichromatism, yet we should keep them all in 

 mind while endeavouring to interpret the results of future field 

 studies or experimental researches along these lines." Australia 

 offers a splendid field to the workers of every State for such 

 research. No student need say the field is without opportunity. 

 It is there, and one full of interest. The study of our desert 

 forms is a live one for those living far back, while for the coastal 

 people the plumages of PacliycepJiala are full of interest — the 

 foundation of the rufous race geographically, the " medieval " 

 period of greys, and the modern species of many colours — the 

 three phases showing in any one male bird in three years. 



Mr. Beebe draws attention to Munia flavipryvina as being a 

 desert form of M. castaneitJiorax, and quotes an Australian 

 trapper of great experience for the opposite opinion, in so far as 

 he has always met each bird true to its species. Everywhere 

 there is a field for the man who interests himself in the birds — 

 abroad or in the aviary. 



Some pages (15-18) are given to the question of sporadic 

 melanism. Australia renders its examples. The writer has a 

 good example in a specimen of the White-plumed Honey-eater, 

 the throat being particularly dark, and the body not normally 

 greenish. This species generally appears true to its type. 



In Tasmania there appears to me to be a tendency to 

 melanism, judging by the birds I have recently seen. Pages 

 31-33 are given to " The Direction of Evolution." Melanism 

 in humidity is said to be not subject to mutation and natural 

 selection. One author considers " the direction of evolution can 

 never be reversed ;" another asks, " Can the direction of evolution 

 ever be anticipated } " " Interesting and significant as the 

 results are, they but open up innumerable new vistas of unex- 

 plored fields." 



Mr. Beebe sounds a warning note with regard to naming 

 variations. The scientific world of to-day considers its nomen- 

 clature as near as possible to the natural order of evolution, 

 while it may still remain a help to working naturalists. — R. H. 



