7o8 



NA rURE 



[June 3, 1922 



discrepancy between the value 45-34 and that (45-40) 

 given previously as the weight of selenium equivalent 

 to 18-39 of sulphur. 



Students who read this book carefully in conjunction 

 with their lectures and laboratory work will be in a 

 position to continue their studies in theoretical and 

 practical chemistry with great advantage. 



The Origins of Disease. 



Organic Dependence and Disease : Their Origin and 

 Significance. By Dr. J. M. Clarke. Pp. 113. (New 

 Haven : Yale University Press ; London : Oxford 

 University Press, 1921.) 125. 6d. net. 



THE distinguished palaeontologist who directs the 

 New York State Museum at Albany has here 

 brought together a number of instances of dependent life, 

 tending to or attaining a parasitic habit, as presented 

 by fossils mostly of palaeozoic age. Some of these 

 have long been known, others are due to Dr. Clarke's 

 own skilled observation, but it is useful to have them 

 all assembled. On this foundation is reared an edifice 

 of philosophic conclusions, imposing in its dimensions 

 and decorated with much verbal ornament. But, as 

 in all great architecture^ the main lines of the structure 

 are few and simple, nor do they diverge unduly from 

 accepted tradition. " Disease is any departure from 

 normal living." " Normal Hving means full activity 

 of an unimpaired physiology inclusive of the function 

 of locomotion or mobility." Those who consider the 

 lihes of the field will protest that these definitions are 

 scarcely traditional. True ; but, if they be accepted 

 as interpretations of terminology, the actual theses 

 will not appear so revolutionary. 



The main conclusions are these. Among animals, 

 at any rate, evolutionary progress has been always 

 through those races that have retained full powers of 

 locomotion. The assumption of a stationary mode of 

 life is a step on the primrose path, and that one false 

 step is ne'er retrieved. (Clearly Dr. Clarke does not 

 believe in the fixed ancestor of the echinoderms.) The 

 proportion of forms that retained their freedom was 

 greater in the earhest known faunas. These state- 

 ments are even more applicable to animals that have 

 adopted a life of dependence on others. Simple 

 association precedes either symbiosis or parasitism, 

 and the evolution of a parasitic habit was gradual, 

 extending it may be through many geological periods. 

 This is well exemplified by the history of those simple 

 sea-snails that took up their quarters near the vent of a 

 certain species of crinoid and subsisted on the issuing 

 stream— a history traced from Ordovician to Middle 

 Carboniferous times. In treating of the oldest faunas. 

 Dr. Clarke perhaps trusts too much to negative evid- 

 NO. 2744, VOL. 109] 



ence, but his main lines of argument are reasonable 

 enough. 



It is of the host we speak as suffering from disease ; 

 but the parasite also lives a life that Dr. Clarke calls 

 " abnormal " or even " unrighteous." Neither sin nor 

 disease was " original " with life as a whole. Even the 

 bacterium of the Precambrian was a free and inde- 

 pendent organism. As for man, " it is safe to say that 

 none of his physical ancestors have ever surrendered 

 their physical independence or suffered essential modi- 

 fication through perturbation of their normal activi- 

 ties." Holding such views. Dr. Clarke naturally does 

 not sympathise with some recent attempts to base 

 evolution on pathology. He does not agree, for ex- 

 ample, with Eccles that " The path of evolution is the 

 path of past disease." He might, however, have dis- 

 cussed the further philosophical (or theological) ques- 

 tion, whether sin and disease in a part of creation may 

 not be a necessary condition for the evolution and 

 salvation of the other part. Such lofty subjects may 

 seem remote from the humble invertebrates of palae- 

 ozoic seas, but Dr. Clarke is justified in his claim that 

 a study of life-relations in their simple beginnings may 

 furnish clues to our own social and psychic problems. 



Shallow-water Foraminifera. 



Department of Marine Biology of the Carnegie Institu- 

 tion of Washington. Vol. xvii. : Shallow-water Fora- 

 minifera of the Tortugas Region. By Joseph A. 

 Cushman. (Publication 311.) Pp. 85 + 14 plates. 

 (Washington : Carnegie Institution, 1922.) 



IT is no disparagement of the excellent work which 

 Dr. Cushman has already done to say that his 

 report on the " Shallow-water Foraminifera of the 

 Tortugas Region " marks a significant step in advance. 

 We do not agree with his practice of reviving obsolete 

 generic names, such as Discorbis, Quinqueloculina, and 

 Triloculina ; the first has long been abandoned in 

 favour of Discorbina, and the two latter have become 

 merged in Miliolina. It appears to be undesirable to 

 complicate synonymies by the revival of early names. 

 But, after all, this divergence of opinion is a minor 

 point which, however confusing to the novice, in no 

 way detracts from the value of Dr. Cushman's work 

 to the advanced student. 



The memoir is well worthy of its place amid the 

 zoological literature published by the Carnegie In- 

 stitution of Washington, and its value is increased 

 by a map of the region, some excellent figures in 

 the text, and fourteen plates which compare favour- 

 ably with the illustrations of some of the author's 

 earlier works, their enhanced value lying in the fact 

 that they are original drawings " ad nat.," and not 



