22 



SCIENCE 



[N. S. Vol. XXXVII. No. 940 



tuting the activities of the living cell will be 

 resolved into their individual phases. ... It is 

 relatively easy to obtain a balance sheet repre- 

 senting the intake and output of substances in the 

 animal body, but what is fundamentally necessary 

 for the proper appreciation of this balance sheet 

 is a knowledge of the various chemical transac- 

 tions which (to continue the simile) should be 

 comprised in a trading account. For it is by the 

 proper adjustment and regulation of these trans- 

 actions that the energy represented by food and 

 tissue substance are economically utilized accord- 

 ing to the varying needs of the body. The rapidly 

 developing appreciation of the fact that different 

 proteins, fats and sugars are not physiologically 

 equivalent but that certain definite chemical groups 

 subserve special functions in the animal organism 

 emphasizes the necessity of the study of inter- 

 mediary metabolism. ... A true knowledge of 

 metabolic processes can only be obtained by the 

 tedious unravelling of the complex system of bio- 

 chemical changes into individual chemical reac- 

 tions. At the present time only a few of these 

 simple reactions have been recognized and studied, 

 but even now it requires little imagination to 

 realize that in the future it will be possible to 

 construct an accurately itemized account of the 

 animal body's chemical transactions, both anabolic 

 and catabolic. The value of such knowledge for- 

 the advancement of biology and medicine is suf- 

 ficiently obvious. 



Dakin's book emphasizes the fact that many 

 of the striking biochemical reactions can al- 

 ready be imitated to-day more or less success- 

 fully by experiments in vitro. This is, of 

 course, a helpful assurance, serving to divert 

 attention from vague speculation regarding 

 subtle vital forces. It has been a popular 

 practise to appeal to hypothetical enzymes to 

 explain some of the obscure chemical trans- 

 formations in the organism. Thus we have 

 been wandering through the mazes of the oxi- 

 dases, oxygenases, peroxidases, reductases, 

 catalases and other products of perplexing 

 nomenclature in the hope of escaping the 

 uncertainties of intermediary metabolism. 

 Much of the obscurity is at length dispelled 

 by a vigorous presentation in which questions 

 of chemical structure are paramount and de- 

 tails of biological processes are exempliiied in 

 actual experiment or by clear analogy. 



In connection with the oxidative capacity of 

 the body Dakin points out the accumulating 

 evidence in favor of the hypothesis of super- 

 oxide formation in living cells. With regard 

 to the possibility of biochemical reductions 

 reference is made to the interesting Oanniz- 

 zaro reaction whereby the reduction of one 

 molecule of substance takes place with the 

 simultaneous oxidation of a second molecule, 

 according to the scheme: 



2 R . CHO + K,0 = B . CH,OH + B ■ COOH. 



A brief chapter on the methods of investiga- 

 tion formulates the attitude of mind with 

 which the student of intermediary metabolism 

 approaches his problems. It is a decidedly 

 exceptional outline of the viewpoints which 

 may guide the worker in this field in the 

 direction of successful experimentation. 



Pointing out that it is only since the pub- 

 lication of Knoop's important studies in 1904 

 that any material progress has been made in 

 the experimental investigation of fatty acid 

 katabolism, Dakin subjects Knoop's theory of 

 /3-oxidation to a critical analysis. He shows 

 that chemical analogies for this are found in 

 the behavior of fatty acids towards hydrdgen 

 peroxide, so that by the choice of a suitable 

 oxidizing agent the occurrence of ^-oxidation 

 can readily be demonstrated in vitro. Physi- 

 ological experiments continue to furnish stri- 

 king confirmation of the theory. The relative 

 importance of the ;8-hydroxy- and j8-ketonic 

 acids in the mechanism of the reaction are 

 discussed with abundant reference to the 

 growing illustrative literature to which the 

 author of the monograph has furnished promi- 

 nent experimental contributions. Other types 

 of reaction than that of j8-oxidation have not 

 yet been observed, and it is not likely that 

 a-oxidation of normal saturated fatty acids 

 takes place in the animal body. 



In turn the behavior of the unsaturated 

 acids, the oxidation of acids with branched 

 chains, the dibasic acids, aromatic compounds, 

 amino-, hydroxy- and ketonic acids are re- 

 viewed. The intimate biochemical relation 



