592 



NATURE 



[OcTOliER 20, 1898 



ation have been on the one hand Abbreviation, or the 

 early arrest of development, and Retardation, or the late 

 appearance of the first signs of an organ, acting, together 

 or separately, on regressive organs ; while on the other 

 hand Acceleration, or the early appearance and rapid 

 development of an organ, and Prolongation, or gradual 

 increase in the length of life, are influences to which 

 progressive organs are subject. 



These four factors then, separately or combined, con- 

 dition ontogeny, and hence is formulated the "funda- 

 mental law of organogeny," that the rate of development 

 of an organ is proportional to the degree, at the time, of 

 its phyletic development ; so that ontogeny is a very 

 much modified recapitulation of phylogeny. 



In the development of an individual it is therefore 

 possible to discern two influences at work: (i) the 

 hereditary, recapitulating, phylogenetic influence, and (2) 

 functional epigenesis, due to the direct action of inner 

 and outer causes, such as surrounding organs, food, 

 temperature, gravity, and so on. Mehnert is, perhaps, 

 not as clear as he might be, when he comes to deal with 

 the exact way in which these environmental changes have 

 become inherited ; but (without mentioning Natural 

 .Selection) he seems to tend towards a Lamarckian in- 

 heritance of acquired characters. He discards, however, 

 a chemical pangenesis, and explains the influence of the 

 soma on the germ by a physical theory — analogous to 

 magnetisation — which has at least the merit of being 

 novel. 



At the end of the book are some remarks on the 

 specific variations in embryogeny, and in length of life, 

 and on involution. 



The epigenetic modifications of the phylogenetic order, 

 perhaps the most valuable part of this work, are 

 graphically illustrated by numerous diagrams. 



Practical Plant Physiology. By Dr. W. Detmer. 



Translated from the second German edition by S. A. 



Moor, M.A. (Camb.), F.L.S. (London : Sonnenschein 

 and Co., Ltd., 1898.) 



A TRANSLATION of Detmer's " Pflanzenphysiologische 

 Practicum " will doubtless be very acceptable to students 

 of vegetable physiology in English-speaking countries. 

 Since its publication Detmer's work has always been a 

 standard one, and its second edition was in many ways a 

 great improvement on the first. However, notwithstand- 

 ing the high reputation of the German edition, it seems a 

 pity that the translator should decide that " no sufficient 

 reason has been found for addition or alteration " ; for, 

 with but little extra trouble, a very complete English 

 text-book could have been made of the translation. By 

 including physiological work published since 1895, ^"d 

 by the addition of more complete references to older 

 researches, the usefulness of the book would have been 

 largely increased. 



The German edition has already been reviewed in a 

 previous number of Nature, so that little need be said 

 of the translation. The translator's style is good, and he 

 reproduces faithfully the sketchy and note-book-like form 

 of the original. It may be added that the English 

 edition is well printed, and the illustrations have hardly 

 suffered in their reproduction. H. H. D. 



A Chetnical Laboratory Course. By A. F. Hogg, M.A., 



F.C.S. Pp. 24. (Darlington : James Dodds, 1898.) 

 A SERIES of experiments, arranged to illustrate elemen- 

 tary chemical analysis, are briefly described in this 

 pamphlet. The experiments are arranged to accompany 

 lectures on water, air, combustion, &c., and they form a 

 course of work for the elementary and advanced stages of 

 inorganic chemistry of the Department of Science and 

 Art. Little information is given in addition to instruc- 

 tions for carrying out the experiments. 



NO. I 51 2, VOL. 58] 



LETTERS TO THE EDITOR 



[ The Editor does not hold himself responsible for opinions ex- 

 pressed by his correspondents. Neither can he undertake 

 to return, or to correspond with the writers of, rejected 

 manuscripts intended for this or any other part of NATURE. 

 No notice is taken of anonymous communications.'^ 



Stereo-chemistry and Vitalism. 

 Before commenting on the argument for Vitalism urged in 

 the opening address of Prof. Japp to the Chemical Section of 

 the British Association, it will be best to quote from the report 

 published in Nature such passages as clearly present his 

 position. lie said : — 



" Pasteur's point is, that whereas living nature can make a 

 single optically active compound, these laboratory reactions, to 

 which we resort in synthesising such compounds, always pro- 

 duce, simultaneously, at least two, of equal and opposite optical 

 activity ; the result being intermolecular compensation and con- 

 sequent optical inactivity. . . . 



" If these conclusions are correct, as I believe they are, then 

 the absolute origin of the compounds of one-sided asymmetry to 

 be found in the living world is a mystery as profound as the 

 absolute origin of life itself. The two phenomena are intimately 

 connected for, as we have seen, these symmetric [? asymmetric} 

 compounds make their appearance with life, and are inseparable 

 from it. 



" How, for example, could Itevo-rotatory protein (or whatever 

 the first asymmetric compound may have been) be spontaneously 

 generated in a world of symmetric matter and of forces which 

 are either symmetric or, if asymmetric, are asymmetric in twa 

 opposite senses? What mechanism could account for such 

 selective production? Or if, on the other hand, we suppose 

 that dextro- and Isevo-protein were simultaneously formed, what 

 conditions of environment existing in such a world could ac- 

 count for the survival of the one form and the disappearance of 

 the other ? " 



The last sentence implies the assumption that in the absence 

 of some special unknown cause, the mixed right-handed and 

 left-handed molecules which neutralise each other's optical 

 activities would remain niixed. But is this a valid assumption ? 

 Is there not, contrariwise, a general cause for the separation of 

 them ? Prof. Japp appears to have taken no account of a 

 universal law displayed throughout that continuous redistribution 

 of matter and motion which constitutes Evolution. In the 

 second part of "First Principles" will be found a chapter 

 entitled " Segregation," in which this law and its results are set 

 forth. After illustrations of the process of segregation as it 

 everywhere goes on in astronomic changes, geologic changes, 

 changes in organisms considered individually and as an aggre- 

 gate, changes throughout mental evolution and social evolution, 

 there come at the close of the chapter the following para- 

 graphs : — 



" The abstract propositions involved are these : — First, that 

 like units, subject to a uniform force capable of producing motion 

 in them, will be moved to like degrees in the same direction. 

 Second, that like units if exposed to unlike forces capable of 

 producing motion in them, will be differently moved — moved 

 either in different directions or to different degrees in the same 

 direction. Third, that unlike units if acted on by a uniform 

 force capable of producing motion in them, will be differently 

 moved — moved either in different directions or to different 

 degrees in the same direction." 



A subsequent paragraph argues that by resolution of forces it 

 is demonstrable that any difference between the acting forces, or 

 between the units on which they act, implies the presence of 

 some force, active or reactive, in the one not present in the 

 other ; and that supposing the conditions are such as to permit 

 motion, this differential force must, in virtue of the law of the 

 persistence of force (conservation of energy) produce a differential 

 motion. Hence the corollary is that — 



"Any unlikeness in the incident forces, where the things 

 acted on are alike, must generate a difference between the 

 effects ; since otherwise, the differential force produces no effect, 

 and force is not persistent. Any unlikeness in the things actec 

 on, where the incident forces are alike, must generate a differj 

 ence between the effects ; since otherwise, the differential fore 

 whereby these things are made unlike, produces no effect, 

 force is not persistent." ^ 



1 This passage was written in 1862 at a time when the nomenclature noM 

 current was not established. Hence the use of the word force instead 

 energy. I still, however, adhere to the use of the word persistence, for th 



