162 



KNOWLEDGE. 



Aprii.. 1911. 



these are seven-and-a-half times more effective than 

 those on the Earth, the rotation of the former planet 

 has never been checked b\- lunar action, which in 

 our own case may have been an exceedini;l\- 

 powerful factor in the earlier stages of evolution. It 

 therefore does not seem improbable even from a 

 phvsical standpoint that the length of the Cytherean 

 dav is shorter than it? year, and this supjiosition 

 would meet most of the difficulties we should other- 



wise ha\-e to contend with. There is also, of course, 

 the possiliilitx- of the planet hax'ing a slow retro- 

 grade motion, although this is \'ery unlikely on 

 purel\- d\-namical grt)unds. 



.\ltogether the importance of this rotational ques- 

 tion can scarcely be over-estimated, and the necessity 

 of obtaining further information on a subject about 

 which so much uncertainty exists, opens u\) an 

 admirable field of research for amateurs. 



REVIEWS. 



PHVSICO-CHEMISTKV. 



Thcoric Physico-Cltiniiqiic dc la ]'ic cf Generations 

 Spoiitiini-cs. — By Stephank Lhdlc iProfesseur a I'ecole de 

 ^Icdecine de XantesI, Paris. 204 pages. 57 illustrations. 



(A. Poiiiat. Price 5 francs.) 

 This little book gives an excellent summary of some of the 

 most important physico-chemical processes that take place in 



the presence of certain poisons, but whereas colloidal platinum 

 may be rendered active over and over again, an enzyme such 

 as diastase is destroyed by a moderate degree of heat, and its 

 activity can never be restored. In fact, it might almost be 

 possible to form an enzymic definition of life. \\'hen once an 

 enzyme has been produced without the aid of a living 

 organism the possibility of proving spontaneous generation 

 will be nearer than it is at present. 



AfrJi::,s >J tic Ri^u'itl^iii Kay. 



l-ic.LKi, 1. Dsuiotic drowtli^ 



living organisms, and in particular of osmosis. The author 

 shows by a series of extremely interesting photographs 

 (of which one is reproduced in Figure II, that it is 

 possible by introducing mixtures of certain salts into 

 solutions of other salts to produce, by osmotic pressure, forms 

 analogous to those of plants and the shells of aijuatic animals. 

 These forms may be used as illustrations of the mechanism 

 by which the forms of living organisms were possibly produced, 

 but, in our judgement, it is straining analogy of form too far to 

 regard them as evidence of spontaneous generation. The author 

 does not succeed in bridging the gulf between the force that 

 causes a crystal to form in a certain way and the force that 

 we know as "life." He refers also to the analogy between 

 Bredig's so-called "inorganic ferments" and enzymes such as 

 pepsin and diastase. In both cases the action is inhibited by 



PHYSICS. 



Radinin : Its Pliysics and Therapeutics. — By Dawson 



Turner, M.D., F.R.C.P. S6 + x. pages. 



(Bailliere, Loudon, 1911. Price 5 - net.) 



In this book. Dr. Turner has summarised in a concise yet 



readable form the various researches published in scattered 



scientific journals upon the physical phenomena of radium. 



He has also given a description of the uses to which radium 



has been put as a curative agent, illustrated by outlines of the 



cases and photographs, which are obviously more intended for 



the medical than for the general reader. It is in fact with the 



therapeutic part of the subject that the book mainly deals, and 



it appears to us to be admirably suited as a guide to medical 



men who desire a handy manual upon radium. 



