166 Notices respecting New Books. 



The subject was cultivated by C. L. Dodgson, who called the 

 Determinant a Block, and published a work with this title, which 

 did not reveal his identity with the author of 'Alice in Wonderland.' 

 Another standard work on Determinants is by R. E. Scott, Master 

 of Saint John's College, Cambridge. 



In these days of the Ramification of Research all over the 

 world, a book of this kind is invaluable to the worker in putting 

 him immediately in the fore front of the progress achieved already ; 

 to prevent him from overlapping, and losing time over repetition 

 of what has been done before. 



The Physiology of Vision, with special reference to Colour-Blindness, 

 By E. W. Edkidge-Geeen. Gr. Bell & Sons. 12s. net. 



Card Test for Col our- Blindness. By E. W. Edeidge-Geeen. 

 Gr. Bell & Sons. 25s. net. 



The subject of colour-vision, though largely a branch of physiology, 

 is of peculiar interest to the physicist. Having followed the rays 

 of light from an object as far as the retina, he cannot abandon 

 them there without curiosity as to the machinery by which they 

 are perceived. In the text-books of physics, however, treatment 

 is usually restricted to a brief exposition of the Toung-TIelmholtz 

 theory of colour-vision; and it speaks much for the respect in- 

 spired by these great names that, inadequate as the theory is, it is 

 scarcely ever criticised. Outside the circle of text-book writers 

 it is becoming generally known that the three-colour theory has 

 failed to represent the facts accumulated during the past thirty 

 years, mainly by the efforts of Dr. Edridge-Green, whose name is 

 inseparably connected with the subject. Owing, however, to the 

 fact that his work is mostly contained in short papers scattered 

 over many years in a large number of publications, the points 

 established by him in his experiments, observations, and criticisms 

 are not familiar to many who would like to study them. The 

 book under notice, which will be welcomed by all interested in 

 the problems of vision, should remedy this state of affairs, for it 

 presents concisely, in a very well produced volume, the views 

 developed by the author on the physiology of vision in general. 



The artificiality of the three-colour theory is so obvious that we 

 venture to suggest that nothing but the eminence of its fouuders 

 and supporters has kept it alive so long. From the anatomical 

 point of view it has nothing to commend it, for all attempts to 

 demonstrate three kinds of nerve elements, or retinal elements, 

 have failed signally. Erom the physical and physiological point 

 of view Dr. Edridge-Green has brought forward a series of 

 criticisms which we have never seen successfully refuted. In his 

 chapter on the simple character of the yellow sensation — a sen- 

 sation which on the Toung-Helmholtz theory should, of course, 

 be resolvable into red and green — he adduces sixteen pieces of 

 evidence which, whatever interpretation they may receive, seem 



