230 



NATURE 



[April 21, 192 1 



dorsal organs (such as the nervous system) than 

 the ventral; and the tissues adjacent to the 

 middle line than the outer tissues. The flow of 

 matter and energy along these axes is apparently 

 faster in certain directions, or the developmental 

 impulses are transmitted more rapidly in these 

 directions, than in others. 



In order to test this view, the author has per- 

 formed a number of experiments. He has placed 

 the developing eggs of certain fish in water to 

 which were added substances, such as alcohol and 

 cyanides, that lessened the rate of natural develop- 

 ment, and he placed others under adverse con- 

 ditions, such as intense cold or diminished oxygen 

 pressure. The results of these experiments, made 

 by Prof. Newman, show that those embryos which 

 survived exhibited most retardation in those 

 regions where normal specimens normally reared 

 undergo their most rapid development. On con- 

 tinuing these experiments, however, he found that 

 a certain number of the experimental animals re- 

 covered from this inhibitory effect, and that this 

 recovery is most marked in the very regions which 

 had previously been most depressed. For ex- 

 ample, the development of the head was at first 

 retarded, but if the fish survived this first period 

 of life under experimental conditions, then the 

 development of its head was accelerated, and, 

 indeed, to such a degree as to render it incapable 

 of continued existence. These non-viable embryos 

 exhibited the strangest appearance. Some "con- 

 sisted of nothing but isolated eyes " ; others 

 " merely of heads with large rolling eyes and a 

 tiny indifferentiated appendage that stands for 

 the rest of the body"; others, again, "became 

 broad and flat, like a skate, or high and com- 

 pressed, like a sunfish. In fact, a good assort- 

 ment of experimental monsters will furnish paral- 

 lels to most of the stock types of form-distortion 

 seen in the specialised and degenerate groups of 

 fishes " (p. 161). We can only regret that the 

 author has not reproduced figures and descriptions 

 of these interesting monsters, or given references 

 to the literature. 



These results lead the author to seek for a 

 cause which has acted upon growth and develop- 

 ment during the course of animal history some- 

 what in the way that the depressing agency of his 

 experiments has led to modification of form. The 

 problem is to explain the elongated newt and the 

 truncated frog; in other words, the tendency of 

 animal groups to cephalisation, to abbreviation of 

 the abdominal and caudal regions in the more 

 highly organised members of most classes. Here 

 he has nothing to offer us. He speaks, as so 

 many American writers on biology do, of " the 

 NO. 2686, VOL. 107] 



ageing of the hereditary chromatin " as an internal 

 factor that has operated in preserving, for ex- 

 ample, the neoteric or perennially youthful type 

 of body, or in other ways. He attempts to cor- 

 relate the elongated form of body with the effect of 

 low temperatures acting as a depressing agent. We 

 are put off with phrases such as "lowered rates 

 of chemical metabolism" and "racial senescence," 

 expressions which really have no scientific 

 content. The moral of all this is that we do not 

 know enough evolutionary physiology to enforce 

 conclusions drawn from our anatomical and de- 

 velopmental records of animal structure by con- 

 clusions based on corresponding records of their 

 past and present living processes. The anatomical 

 evidence alone leads to such melancholy exhibi- 

 tions of inconclusive reasoning as are found in the 

 discussions on animal phylogeny in this book; 

 and if the author has not been successful in apply- 

 ing physiological tests to animal pedigrees, we 

 can but applaud his courage in making the 

 attempt. F. W. G. 



Ancient Metal Implements. 



Tools and Weapons : Illustrated by the Egyptian 

 Collection in University College, London, and 

 2000 Outlines from Other Sources. By Prof. 

 W. M. Flinders Petrie. (British School of 

 Archaeology in Egypt and Egyptian Research 

 Account, Twenty-second Year, 1916.) Pp. 

 vii + 71 -)-lxxix plates. (London: British School 

 of Archaeology in Egypt; Constable and Co., 

 Ltd. ; Bernard Quaritch, 1917.) 35^. net. 



ONE of the ever-present problems of archae- 

 ology is the degree of interdependence in 

 which the ancient civilisations stood to one another 

 in the matter of customs, rehgion, and the material 

 objects of everyday life. Where undoubted im- 

 portations occur the question becomes simple, but 

 in the early ages of man's civilisation these 

 imports are more often lacking, and the sole evi- 

 dence available comes from a typological com- 

 parison of various classes of objects. In the 

 volume under review Prof. Flinders Petrie has 

 devoted himself to a study of Egyptian im- 

 plements other than most of the stone types, and 

 by the aid of numerous figures of similar imple- 

 ments from other countries, chiefly in Europe and 

 \\'estern Asia, he has sought to demonstrate the 

 part played by Egypt in the invention and develop- 

 ment of the various tools and weapons known to 

 the ancient world. 



If one fact emerges more clearly than another 

 from this study, it is the extraordinarily small 



