Ki{\ii^:\vs. 



niOCHEMISTKV. 



Oxiii<itioii.i ami Reductions in the Auiiiuil lioily. — Hy 

 II. I). Dakin, D.Sc, F.I.C. 135 pages. 9Mns..X6iMS. 



(Longmans, Green & Co. Price 4s. net.) 



This volume forms one of the excellent series of monographs 

 on biochemistry now being issued under the general editorship 

 of Prs. K. H. A. Pliiiimer and F. G. Hopkins. Biochemistry, 

 though <|uite a young science, is a rapidly-growing one, and 

 this series, therefore, supplies a very real need. A series of 

 short monographs, moreover, has the advantage over a large 

 text-book covering the whole ground that it may more easily 

 be kept up-to-date, by revising volumes when necessary. 



The present book gives a full account of the work that 

 has already been done on oxidations and reductions in the 

 animal body. As to the latter, not much seems to be known. 

 Everyone is aware, however, that many compounds (e.g., 

 carbohydrates) containing carbon and hydrogen are oxidised 

 in the animal body to carbon-dioxide and water, thereby 

 producing the heat necessary to life ; but it is in very few 

 cases that these simple compounds are produced immediately 

 from the complex ones ; more generally they result from long 

 series of katabolic changes, and the study of the intermediate 

 compoimds produced is not only of interest and importance 

 for the chemist, but also for the physician. 



The course of oxidation in the animal body does not as a 

 rule follow that obtained in vitro by the use of the ordinary 

 laboratory oxidising agents, but it can generally be obtained 

 in fitro by the use of hydrogen peroxide. It seems likely. 

 therefore, that oxidations in the body are produced by means 

 of unstable superoxides. Fatty acids undergo oxidation only 

 in the fi position, a truly remarkable change, which can only 

 be produced in vitro by the aid of hydrogen peroxide. 

 Knoop studied the fate in the body of fatty acids in which a 

 resistant radical had been introduced, as otherwise complete 

 oxidation generally results. He found that whilst benzoic and 

 phenylacetic acids were unoxidised. phenylpropionic and 

 phenylvaleric acids were converted to benzoic acid and 

 phcnylbutyric acid to phenylacetic acid (of course, the 

 products obtained from the urine were combined with urea), 

 and was thus led to the above generalisation. In support of 

 this theory it may also be mentioned that only those fatty 

 acids yield acetoacetic acid when perfused through a surviving 

 liver which contain an even number of carbon atoms, showing 

 that the acetoacetic acid results by continued oxidation in the 

 fl position. 



The contents of the book have been admirably arranged, 

 and its value is enhanced by the inclusion of a very complete 

 bibliography. The only point we are inclined to criticise is 

 that the diagram on page 66, showing the conversion of 

 phenylalanine into acetoacetic acid in the body, is apt to give 

 the impression that phenylacetic acid when perfused through 

 a surviving liver as an intermediate product, which is not the 

 case, since, as Dr. Dakin points out, phenylacetic acid, if 

 administered, is excreted without oxidation as phenaceturic 



acid. no ri 



H. S. Redgrove. 



BIOLOGY. 



The Mechanistic Conception of Life. Biological Essays. — 



By jACyUE.s Loi:b,M.D., Ph.D., Sc.D. 232 pages. 58 figures. 



8;J-in.X5^in. 



(The Cambridge University Press. Price 6, ■ net.) 



This volume contains ten essays (reprinted from various 

 sources) dealing for the most part with experimental biologv. 

 Interspersed, however, are occasional metaphysical specula- 

 tions and criticisms of other metaphysical specuLations ; and 

 the main object of the writer seems to be to illustrate and 

 enforce the theory laid down in the essay which gives the title 



to the volume. The mechanistic conception of life which the 

 author advances is that the sum of all life phenomena can be 

 unequivocally explained in physico-chemical terms. But a 

 complete scientific account of life must take account of all the 

 relations involved therein, and. as Professor Lloyd Morgan has 

 pointed out, there is absolutely no justification for excluding 

 the conscious relation- And, however far it may be possible 

 to explain all biological phenomena in terms of matter and 

 motion (or inertia and energy) — and certainly physical 

 science is justified in making the attempt — Huxley's objec- 

 tion still holds that we know matter and motion only as 

 forms of consciousness, and hence, no explanation of 

 consciousness is logically possible in terms of matter and 

 motion. As a specimen of Dr. Loeb's metaphysics the 

 following may be quoted — " Nobody doubts that the durable 

 chemical elements are only the product of blind forces " — 

 but does any metaphysician believe it ? 



The speculative portions of Dr. Loeb's essays (with their 

 hypostatising of force, and confusion between a scientific 

 accoimt of phenomena aiming at co-ordination of relations 

 and a metaphysical explanation of the source of phenomena) 

 need not be taken very seriously. It is better to ignore all 

 such speculations and pay attention only to the purely scienti- 

 fic portions of the book. These will be found full of interest 

 and value by scientific men who are not sutliciently specialists 

 in biology to wish to consult the original memoirs of Dr. Loeb's 

 and other investigators' experiments. Dr. Loeb's experiments 

 in artificial parthenogenesis are particularly important, and 

 throw much light on the physico-chemical aspect of fertiliza- 

 tion. It appears that, in the case of the eggs of the sea- 

 urchin, and some other cases, two processes are necessary 

 for fertilization. First, the cortex of the egg must be cytolized, 

 to allow the formation of what is termed a fertilization 

 membrane. This can be artificially brought about by 

 means of butyric acid. The spermatozoon probably effects it 

 by means of a lysin. The second process seems to be of a 

 corrective nature. It can be brought about artificially either 

 by placing the egg in hypertonic sea-water containing oxygen, 

 or in isotonic sea-water free from oxygen (or containing a 

 trace of potassium cyanide, which prevents oxidation!, after 

 which it is transferred to ordinary sea-water. 



There are also interesting accounts of various tropisms. 

 the heliotropism of the aphid being particularly remarkable. 

 Indeed, in this respect the aphid behaves just like a machine, 

 and Dr. Loeb's explanation, in terms of the action of light, 

 through the optic nerve, upon one of a pair of symmetrical 

 muscles, is probably correct. But it is well to remember 

 that all the actions even of an aphid are not of the nature of 



foi^'^'"^' H. S. Kki.crovk. 



Aristotle's Researches in Natural Science. — By Thomas 



East Lones, M..^., LL.D. 274 pages. 10 illustrations. 



8Mn.X5Mn. 



(West, Newman & Co. Price. 6 • net.) 



The writer of this book has undertaken a useful and an 

 interesting task. It is no other th.an to clear a ro;id for the 

 student of .Aristotelian science by setting forth, in the order 

 and style of a modern text-book, the main facts of .-\ristolle's 

 scientific knowledge and teaching. While in some of .-Aristotle's 

 philosophical treatises his style is in the highest degree polished 

 and clear, this is not always the case in his writings, and it is 

 certainly not so, for instance, in his History of .-Animals. This, 

 and some of the other books, are full of repetitions and seem 

 strangely disordered: so much so that critics sometimes speak 

 of them as having comedown to us in the form of mere lecture 

 notes, never set in order for publication. .-Vccordingly, with 

 all the help that translations can give us. it is not easy to find 

 out what .-Vristotle precisely -said, or what he probably knew, 

 regarding any particular thing ; still more is it difficult to get 



