NA TURE 



327 



THURSDAY, NOVEMBER 21, 1912. 



THE MECHANISTIC CONCEPTION OF 

 LIFE. 



The Mechanistic Conception of Life. Biological 

 Essays by Dr. Jacques Loeb. Pp. vi + 232. 

 (Chicag-o, Illinois : University of Chicago 

 Press ; London : Cambridge University Press, 

 n.d.) Price 6s. net. 



THIS book deals for the most part with facts 

 derived from the author's own experimental 

 work. The facts are set forth in a manner easily 

 to be understood, in a series of essays, most of 

 which have already appeared in print, and the 

 general nature of which can be inferred from their 

 titles, viz., the significance of tropisms for psycho- 

 logy ; the comparative physiology of the central 

 nervous system ; pattern adaptation of fishes ; 

 physiological morphology; the nature of fertilisa- 

 tion ; the nature of formative stimulation ; the pre- 

 vention of death by fertilisation ; the role of salts 

 in the preservation of life ; the influence of en- 

 vironment on animals. That these diverse sub- 

 jects are closely interwoven and that the facts 

 which are cited point to a definite conclusion re- 

 garding the nature of life is demonstrated in the 

 first essay, which gives the title to the work, and 

 it will be best to confine attention mainly to that 

 one, since it would require more space than the 

 Editor could fairly be expected to place at my 

 disposal to deal at any length, and in the manner 

 it deserves, with each individual paper of the 

 series. 



The results at which Prof. Loeb has arrived are 

 best expressed, wherever possible, in his own 

 words — they are, indeed, stated so clearly and 

 concisely that it would be superfluous to attemnt 

 to set them forth in other language than that 

 which he has himself employed. 



In connection with phenomena characteristic 



of life, he begins by pointing out that the first 



I attempt to reduce such a phenomenon — that of the 



I production of animal heat — to physico-chemical 



I terms was made as long ago as 17S0 by Lavoisier 



and Laplace, an attempt which has now been 



successfully converted into accomplishment. As 



the author remarks, this work touches the core 



of the problem of life, since "oxidations form a 



part, if not the basis, of all life phenomena in 



higher organisms." 



With regard to the so-called "riddle of life," 

 Prof. Loeb of necessity admits that we are not 

 yet able to give an answer to the question as to 

 how life originated on the earth. Whilst leaning 

 towards the idea of .^rrhenius that life germs may 



I be driven through space by radiation-pressure, he 

 NO. 2247, VOL. 90] 



emphasises the necessity of attempting the " other 

 problem "■ — that, namely, of producing living 

 matter artificially. The kind of living matter that 

 he expects to be thus produced is that which con- 

 stitutes nuclear substance. For the nucleins have 

 the peculiarity of acting on ferments for their own 

 synthesis, and thus reproducing themselves. Who- 

 ever claims to have succeeded in making living 

 matter from inanimate will have to prove that he 

 has succeeded in producing nuclear material which 

 acts in this way. " Nobody has thus far succeeded 

 in this, although nothing warrants us in taking 

 it for granted that the task is beyond the power 

 of science." 



Regarding fertilisation of the egg, it is shown 

 that only a short while ago this was still 

 " shrouded in that mystery which to-day surrounds 

 the origin of life in general," but the problem is 

 to-day reduced to physico-chemical terms, since 

 activation is determined by chemical or even by 

 mere physical agencies. 



Discussing the question of the nature of life and 

 death, " which occupies the interest of the layman 

 perhaps more than any other problem," the author 

 remarks that "we can well understand that 

 humanity did not wait for experimental biology *^o 

 furnish an answer. The answer assumed the 

 anthropomorphic form characteristic of all explana- 

 tions of nature in the prescientific period. Life was 

 assumed to begin with the entrance of a "life- 

 principle into the body. . . . Death was assumed 

 to be due to the departure of this ' life-principle. ' " 

 Scientifically, however, individual life " begins with 

 the acceleration of oxidation in the egg," and 

 "ends with the cessation of oxidation in the body." 

 The problem of the beginning and end of individual 

 life is thus physico-chemically clear, and the doc- 

 trine of a "life-principle" must be abandoned. 



Dealing with the subject of heredity, an in- 

 teresting account is given of the discovery of the 

 sex chromosomes and their relation to the Men- 

 delian theory. Whilst admitting that science has 

 yet to determine the chemical substances in the 

 chromosomes which are responsible for hereditar\- 

 transmission of qualities and the mechanism by 

 which they act, the author shows that a com- 

 mencement has already been made, since it is 

 known that for the formation of a certain black 

 pigment transmitted through the male element, the 

 cooperation of tyrosin and tyrosinase are re- 

 quired, and the chromosome must carry sub- 

 stances which determine the formation of these. 

 " While until twelve years ago the field of heredity 

 was the stamping ground for the rhetorician and 

 metaphysician, it is to-day perhaps the most exact 

 and rationalistic part of biology." Thus the pheno- 

 mena of fertilisation and heredity, which "are 



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