340 SCIENCE PROGRESS 



whose interest is not so direct, there is much that will fully repay the expenditure 

 of time in its perusal. 



Of the fourteen chapters the first two deal particularly with the physical forces 

 and effects of tide and current. Chapter III. is concerned with the foreshore in 

 its various aspects, not least of which is its legal status. The function of vegetation 

 next receives attention, and this is followed by a treatment of dunes, shingle 

 beaches, and salt marshes, and their fixation by plants. Two chapters are 

 occupied with the description of constructional works in relation to reclamation, 

 erosion, and accretion. The final sections treat of Blakeney Point from the 

 engineering standpoint, State and local control, and complementary problems. 

 Appendices follow which furnish data regarding the characteristic species of the 

 various habitats, and a list of authorities having powers and duties in relation to 

 defence against the sea. 



Apart from the major theme the authors touch on several points of practical 

 interest of which we may especially cite the economic potentialities of these waste 

 areas, as exemplified by the value of Psamma in paper making and the use of 

 dunes and even shingle for afforestation. In the latter connection the suggestion 

 of Pinus insignis for the one and Alnus incana for the other is noteworthy. 



We cannot conclude this review without reference to the numerous and well- 

 chosen illustrations, many of which are from photographs portraying coastal 

 phenomena in a wide range of localities. 



E. J. Salisbury. 



MEDICINE 



Tumours : their Nature aud Causation. By W. D'este Emery, M.D., B.Sc. 

 [Pp. xx + 146.] (London : H. K. Lewis & Co. Price $s. net.) 



In this book, which is an essay in support of the parasitic theory of the origin ot 

 tumours, Dr. D'este Emery argues with much skill that neoplasms may best be 

 explained as cell reactions in response to the invasion of a specific organism. 

 The author has no new observations to bring forward, but, assuming the presence 

 of a parasite possessed of very definite characters, he attempts to show by analogy 

 with other undoubtedly parasitic diseases that cancer may reasonably be placed in 

 the same category. 



For the cancer parasite Dr. Emery postulates the following properties : (1) It 

 must be of so small a size as to escape observation by any means at our disposal 

 at present. (2) For some part, at least, of its life-history it must inhabit the cell, 

 or, perhaps, its nucleus. (3) It must produce a toxin which has the power to 

 induce cell division. It is also assumed that the parasite has a long latent period, 

 and that it infects the cell in very large numbers. 



Even if the possibility of the existence of such an organism be granted — and 

 there is, of course, no actual proof of this— its entrance into the body is still to be 

 explained. If the author's conclusions are correct it should surely be possible to 

 effect an artificial infection of healthy tissues by the inoculation of whole or 

 disintegrated cells containing large numbers of parasites. But this has never 

 been done, and it is not even possible to be certain that tumours growing in the 

 body are ever able to infect neighbouring healthy cells. Dr. Emery deals with 

 both these objections, but not, we think, convincingly. He certainly acknowledges 

 the possibility of such an infection, and quotes, as an example of transference by 

 contact, an isolated observation by Borrel, which, however, is itself open to 

 doubt ; but he does not explain why, if it can occur at all, it does not do so more 

 frequently. 



