September 23, 192c] 



NATURE 



103 



methods, the o priori and the experimental, 

 decided. 



Prof. Whitehead sees very clearly and expresses 

 very boldly the philosophical problem of Nature. It 

 is admirably expounded in his chapter on "Theories 

 of the Bifurcation of Nature." By bifurcation he 

 means that Nature is presented first in sense- 

 awareness and then in a conceptual activity of 

 thoug'ht. Though the two consequent forms, 

 sense-images and concepts, are inseparable, they 

 are so absolutely distinct that when we reflect on 

 them they present themselves as two totally 

 different kinds, or orders, of facts, between which 

 the relation, so far from being obvious and trans- 

 parent, is literally incomprehensible. For not only 

 is our sense-awareness fragmentary, requiring an 

 activity of conception to complete it — as when, for 

 example, we conceive another side of the moon — 

 but also the fragmentary appearances themselves 

 are referred to another kind of reality, conceived 

 as existing in itself and called Nature. Physical 

 science treats of electrons, aether waves, and such 

 like, as existent entities, sense-awareness being a 

 special form of the relation of these to the mind. 

 This old philosophical problem has recently forced 

 itself on the attention of physicists by reason of the 

 startling r\ature of Einstein's special and general 

 relativity principle. In fact, Einstein may truly be 

 said, adapting the famous phrase of Kant, to have 

 roused physicists from their dogmatic slumber. 

 Prof. Whitehead treads the new ground confi- 

 dently, but yet with caution. He will not have the 

 "curvature of space," and he insists that the con- 

 <:ept of Nature shall concern the reality of the 

 observation, unconfused with any question con- 

 cerning its relation to the observer and his system. 

 To deny the possibility of this detachment is in his 

 view not simple scientific scepticism, but destruc- 

 tion of the basis on which any physical science can 

 be constructed. 



(2) The lectures of the late Prof. Royce, originally 

 entitled " Asp>ects of Post-Kantian Idealism," were 

 first delivered in 1906, and therefore antecede the 

 apparition of the Principle of Relativity. This is 

 not very important, because that principle pro- 

 pounded nothing in the least strange and un- 

 familiar to philosophers. It is, indeed, essentially 

 one and identical with the principle of idealism. It 

 is its confirmation by experiments which has 

 brought it home with such force to the scientific 

 worker. Although, therefore, the lectures arc 

 largely historical, and deal with a philosophical 

 movement and speculation a century old, they are 

 vitally relevant to our present problem. The 

 problem of post-Kantian idealism was essentially 

 the problem of Nature, in particular the fact that 

 while Nature is a concept brought to birth by the 

 NO. 2656, VOL. 106] 



mind itself in its intellectual activity, under the 

 stimulus and out of the material provided for it by 

 sense-awareness, yet this concept stands before the 

 mind as necessarily independent and alien in its 

 existence, and as the ground of the existence of 

 the mind itself. 



It is curious how, in the historical retrospect of 

 the important philosophical movement which fol- 

 lowed Kant, Hegel overshadows all his contem- 

 poraries. One of the most interesting portions of 

 this book is the account of the wonderfully, 

 brilliant work of Schelling, especially in his early 

 period. No physicist has grappled the problem of 

 Nature with greater zeal or with keener insight 

 than this philosopher. 



It is not our purpose to pass judgment, but we 

 commend these two books — both remarkable for 

 their lucidity and intellectual honesty — to all who 

 wish to have a comprehensive grasp of the physical 

 and metaphysical problem of the concept of 



Nature. 



H. WiLDON Carr. 



The Vehicles of Hereditary Qualities. 



The Physical Basis of Heredity. By Prof. T. H. 

 Morgan. (Monographs on Experimental Bio- 

 logy.) Pp. 305. (Philadelphia and London : 

 J. B. Lippincott Co., 1919.) Price los. 6d. net. 



SO far as the study of heredity means formulat- 

 ing and explaining the resemblances and 

 differences between successive generations great 

 progress has certainly been made, and Prof. 

 Morgan thinks it is mock modesty to refrain from 

 ' saying that many problems have been solved. 

 The present book is a masterly account of recent 

 work on the physical basis of inheritance, which 

 means, for practical purposes, the chromosomes 

 of the germ-cells. The general evidence in sup- 

 port of the chromosomal theory is once more dis- 

 cussed ; its fundamental propositions are clearly 

 stated and abundantly illustrated ; and numerous 

 recent subtleties, at varying levels of probability, 

 are explained. The book is indispensable to seri- 

 ous students of biology. 



The first general principle is Mendel's law of 

 segregation. The fertilised ovum contains paired 

 factors or genes, causally linked with certain 

 characters ; these come into relation to each other, 

 but separate off cleanly in the germ-cells of the 

 offspring, one member of each pair going to one 

 daughter-cell, the other member to the other cell. 

 It is during maturation that the conjugation of 

 homologous (paternal and maternal) chromosomes 

 occurs and is followed by their subsequent segre- 

 gation. In all probability, apart from hybrids 

 altogether, the germ-plasm of each immature 



