HARDWICKE'S SCIENCE-GOSSIP. 



265 



A GOSSIP ABOUT NEW BOOKS. 



"NEW BOOK," 

 by Alfred Russell 

 Wallace, the co- 

 discoverer with 

 Darwin of the Law 

 of Natural Selec- 

 tion, is an event to 

 most naturalists. 

 No other scientific 

 writer exceeds him 

 in his clear mar- 

 shalling of facts, 

 and none equals 

 him in his power 

 to see inferences 

 and meanings un- 

 perceived before. 

 His generalisa- 

 tions are of so 

 brilliant a charac- 

 ter as to carry the 

 reader irresistibly along in the flood-tide of the 

 author's speculations, without leaving to him the 

 power of protesting ! Island Life, by A. R. Wal- 

 lace (London : Macmillan & Co.), is in every 

 sense of the word worthy of its industrious and gifted 

 author. It abounds with new and striking gene- 

 ralisations, sometimes almost too rapidly crowding 

 on each other's heels. As regards the contents, the 

 first part has in reality nothing to do with the title, 

 which applies only to the second part of the work. 

 The former is taken up chiefly in discussing the 

 causes of Glacial and Tropical Climates in the 

 Northern Hemisphere, in which he shows that 

 Dr. Croll's theory of the high eccentricity of the 

 earth's orbit, with winter in aphelion, is not sufficient 

 to produce the former without the aid of such 

 geographical conditions as high lands within the 

 Arctic circle to condense vapours into snow. Simi- 

 larly he prefers to fall back upon Sir Charles Lyell's 

 theory (but without altogether ignoring or opposing 

 Dr. Croll's) that the warm climate indicated by the 

 fossil plants and animals of the Arctic regions might 

 be produced by warm oceanic currents, provided 

 there were no high lands. We do not think all 

 No. 192. 



geologists are so ready to concede the point which 

 Mr. Wallace requires for his theory of the geo- 

 graphical distribution of animals and plants in 

 geological times, that the continental land masses 

 and great oceans have been permanent during all 

 geological time. Nor do we think Mr. Wallace is 

 so dependent on this conclusion as he appears to 

 imagine. Mr. Mellard Reade's paper on the subject 

 in a recent number of the " Geological Magazine " 

 is all but unanswerable. Mr. Wallace is occasionally 

 obliged to adopt the practice of minimising an op- 

 ponent's argument and unduly strengthening his own 

 weak one, as when he compares the analyses of oceanic 

 ooze with those of chalk, in order to prove that the 

 latter was a shallow-water deposit ; notwithstanding 

 the close resemblance and even identity of most 

 of its microzoa to those from the bottom of the 

 Atlantic and Pacific. He forgets that in the pure 

 white chalk a good deal of segregation has taken place 

 — the silica into flint, the iron into nodules of pyrites, 

 and frequently even the alumina into reddish argil- 

 laceous concretions — all of which operations have left 

 the chalk relatively much richer in carbonate of 

 lime. If chalk be formed like the white mud in the 

 neighbourhood of coral reefs, how is it we find few 

 or no reef-building corals fossilised in the chalk, and so 

 many of the others ? It is not because the conditions 

 were unfavourable to the preservation of the former. 

 Again, if the Pacific and Atlantic have always been 

 oceans, we may reasonably expect that along their 

 floors the oceanic sediments of every geological epoch, 

 from the Laurentian to the Human have been con- 

 tinuously and uninterruptedly deposited ! 



But although we do not thus far agree with 

 Mr. Wallace, the objections we have named are 

 small in comparison with the important character 

 of this book. In it the reader will find, popularly 

 digested and attractively described, all the generalisa- 

 tions and conclusions made by the author in his larger 

 work on The Geographical Distribution of Animals. 

 The intimate relationship between biological and 

 geographical changes, particularly as exemplified on 

 such great islands as Madagascar, reads as attractively 

 as one of George Eliot's novels. This work is one 

 of those splendid contributions to the doctrine of 



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