224 



SCIENCE. 



[N. S. Vol XII. No. 293. 



The field embraced in the present work is 

 the East Indian Archipelago, or ' the island- 

 world from Sumatra to the Solomon Islands 

 and from the Philippines to the Lesser Sun- 

 das,' as shown in maps 1 and 2 accompany- 

 ing the work. This area extends from Lat. 

 2° N. to 6° S., and from Long. 118° to about 

 127° E. It thus includes not only Celebes, but 

 ' the Talaut Islands in the north, the Sulu 

 Islands in the east, and the Djampa Group in 

 the south.' It thus extends to the Philippines 

 on the north, to Borneo on the west, and to 

 Papuasia on the east. The Introduction (pp. 

 1-130) includes a summary of ' Travel and Lit- 

 erature,' from the visit of Labillardiere in 1793 

 to the expedition of Waterstradt to the Talaut 

 Islands in 1897, with a special list of the litera- 

 ture on Celebes. Next are discussed the ' Sea- 

 sons and Winds in the East Indian Archipelago ' 

 (with maps 3 and 4), in relation to their effect 

 upon the dispersal, distribution, and climatic 

 variation of the birds. This chapter gives a 

 vast amount of information regarding the sea- 

 sons and general climatic conditions of the 

 various groups of islands from Borneo to New 

 Guinea. 



Under the heading ' Migration in the East 

 Indian Archipelago ' the general subject of mi- 

 gration is most intelligently considered, as well 

 as the local movements and migration proper of 

 the birds in the various islands. Although there 

 is here a true migration of marked proportions, 

 little as yet appears to be known as to its de- 

 tails, owing to the lack of competent resident 

 observers. 



' Variation ' is considered under the follow- 

 ing five heads : 1. Individual Variation ; 2. 

 Geographical Variation ; 3. Seasonal Changes ; 

 4. Sexual Differences ; 5. Changes depending 

 upon Age. Under ' Geographical Variation ' 

 these authors so well express the general con- 

 census of ornithologists respecting the origin 

 of new forms through geographic influences that 

 the following statements seem of sufficient in- 

 terest to warrant transcription: " Although it 

 is conceivable, and indeed likely, that a new 

 species may sometimes owe its origin to di- 

 morphism * * * it is nevertheless far more cer- 

 tain that the great majority of the peculiar 

 forms of Celebes and the neighboring islands 



are what are termed geographical species or 

 local races, which have developed their distinc- 

 tive characters while geographically isolated 

 from one another. In the Celebesian area there 

 are about 150 species of this description now 

 known, not to speak of a large number of par- 

 tially formed races. The latter are in many 

 respects the most interesting, as they show 

 species in the first stages of their differentia- 

 tion, and their study holds out the best hope of 

 solving the problem of the origin of species — 

 or at least of the majority of species. The dif- 

 ferences seen are often very small, but of a very 

 palpable description * * *. These differences 

 may be due to an inherent tendency in the indi- 

 viduals in question to evolve in a certain direc- 

 tion * * * , or they may be caused by local 

 influences. For some cases the former assump- 

 tion appears unavoidable ; for other cases there 

 is satisfactory evidence of the effect of local 

 influences, though the exact nature of this 

 latter is almost always uncertain ; as a rule, 

 probably, both causes operate together, but it 

 very rarely happens that an opinion either way 

 is permissible at present." Following this 

 many instances of ' correlated geographical 

 variation ' in size and coloration are cited as 

 characterizing representative forms in different 

 groups of islands. 



The subject of ' Sexual Differences,' so pro- 

 lific of hypotheses, is treated at length, and 

 with admirable conservatism. Eight of the 

 leading ' theories of the origin of secondary 

 sexual characters ' are stated and made the sub- 

 ject of comment ; six of them are presumed to 

 have been ' actually operative in nature, work- 

 ing alone or more likely in different combina- 

 tions and degrees.' Eeasons are also advanced 

 in support of ' the opinion that mutilations of 

 feathers — and hence of other parts — if repeated 

 for generations — are inherited.' 



Under the caption ' Changes dependent upon 

 Age ' are discussed such interesting topics as 

 'ancestral characters,' 'hereditary effects of 

 shelter and exposure,' etc., including the 

 origin of ' racket-feathers ' in groups of birds 

 of very diverse affinities. 



Some fifty pages are devoted to ' Geograph- 

 ical Distribution,' in which 'Wallace's Line' 

 is considered at length. He leaves the prob- 



