504 



THE POPULAR SCIENCE MONTHLY. 



teachers in schools. Several years ago I heard 

 of its introduction at Rugby. 



" To its great efficiency, both as a means of 

 producing interest in geometry and as a mental 

 discipline, I can give personal testimony. I 

 have seen it create in a class of boys so much 

 enthusiasm that they looked forward to their 

 geometry-lesson as a chief event in the week. 

 And girls initiated in the system by my father 

 have frequently begged of him for problems to 

 solve during their holidays. 



" Though I did not myself pass through it 

 for I commenced mathematics with my uncle 

 before this method had been elaborated by my 

 father yet I had experience of its effects in a 

 higher division of geometry. When about fif- 

 teen, [ was carried through the study of per- 

 spective entirely after this same method: my 

 father giving me the successive problems in 

 such order that I was enabled to solve every 

 one of them, up to the most complex, without 

 assistance. 



" Of course, the use of the method implies ca- 

 pacity in the teacher, and real interest in the 

 intellectual welfare of his pupils. But given the 

 competent man, and he may produce in them a 

 knowledge and an insight far beyond any that 

 can be given by mechanical lesson-learning. 

 "Very truly yours, 



" Herbert Spenceb." 



The Geographical Distribution of Ani- 

 mals, with a Study of the Relations of 

 Living and Extinct Faunas as elucidat- 

 ing the Past Changes of the Earth's 

 Surface. By Alfred Russell Wallace. 

 Two vols. With Maps and Illustrations. 

 New York : Harper & Brothers. Pp. 

 1110. Price, $10. 



This work has grown out of the recent 

 progress of biological science, and could 

 neither have been produced earlier than it 

 has been, nor probably by any other living 

 author. To those who regard the evolution 

 hypothesis as a piece of mere useless specu- 

 lation, it may be replied that it is the most 

 powerful stimulus to investigation in the 

 higher science of living things that has yet 

 been known, of which the noble work be- 

 fore us is incontestable proof. The problem 

 of animal distribution is here so conceived 

 and presented as to give it very much the 

 character of a new subject. 



Up to this time, a naturalist has only 

 needed to try to learn about the fauna of 

 any country to be made aware of our lack 

 of knowledge in this field. Much has been 

 learned, of course,, but the records were frag- 

 mentary and scattered, and it was only on 

 the shelves of the best zoological libraries 

 that anything approaching completeness 



was to be found, so that practically such 

 information has been inaccessible. But 

 with the growing interest in Darwinism 

 there came an appreciation of the value of 

 the study of distribution, and a demand 

 arose which made itself felt. As is always 

 the case, the demand only needed to be- 

 come urgent to insure a supply. And it 

 was to meet this want, growing daily more 

 pressing, that Mr. Wallace put forth this 

 work and the task could not have fallen 

 into better hands. His life has been one 

 of preparation for it. As early as 1848 he 

 embarked with Mr. H. W. Bates for the 

 Amazons, and in that region the richest 

 in animal life and later in the Malay Ar- 

 chipelago, the best years of his life were 

 given to the study of zoology. Few of our 

 readers need to be reminded that in those 

 far-away lands he independently worked 

 out the theory of "natural selection." The 

 more difficult work of establishing the 

 validity of the " doctrine of descent" fell 

 into other and, as Mr. Wallace modestly and 

 gracefully says, abler hands ; but he has not 

 ceased to work in that field, and has given 

 great aid in searching out relevant facts 

 and showing their bearings. This work is 

 certainly one of the most valuable of these 

 contributions. From the scattered sources 

 he has, with infinite pains, collected the 

 details of that which was known, and, ar- 

 ranging them with a skill and method which 

 leave little to be desired, has put them 

 within the reach of all. 



The book sets out with an introductory 

 chapter, showing the inadequacy of the 

 popular notion that the manner in which 

 animals are dispersed over the globe is due 

 to diversities of climate and vegetation. 

 Much as there undoubtedly is to give rise 

 to this belief, a little examination shows 

 that no such off-hand treatment will do. 

 That South Africa has lions and giraffes, and 

 Australia kangaroos and other marsupials, 

 finds no explanation in differences of soil 

 and climate, because no marked differences 

 exist. So, too, the theory fails when we 

 find Europe destitute of raccoons, opos- 

 sums, and humming - birds, and North 

 America without hedgehogs or true fly- 

 catchers, although the conditions of life are 

 in all essentials similar in the two regions. 

 Assuming the view that each species 



