January 21, 1915] 



NATURE 



577 



studies on variation and heredity seemed significant 

 mainly as a means of approach to the problems of 

 evolution. The post-Darwinians awoke once more to 

 the profound interest that lies in the genetic composi- 

 tion and capacities of living things as they now are. 

 They turned aside from general theories of evolution 

 and their deductive application to special problems of 

 descent in order to take up objective experiments on 

 variation and heredity' for their own sake. This was 

 not due to any doubts concerning the reality of evolu- 

 tion or to any lack of interest in its problems. It 

 was a policy of masterly inactivity deliberately adopted ; 

 for further discussion concerning the causes of evolu- 

 tion had clearly become futile until a more adequate 

 and critical view of existing genetic phenomena had 

 been gained. Investigators in genetics here followed 

 precisely the same impulse that had actuated the 

 embryologists ; and they, too, reaped a rich harvest of 

 new discoveries. Foremost among them stands the 

 re-discover)' of Mendel's long-forgotten law- of here- 

 dity — a biological achievement of the first rank which 

 in the year 1900 suddenly illuminated the obscurity in 

 which students of heredity had been groping. Another 

 towering landmark of progress is De Vries's great 

 work on the mutation theory, published a year later, 

 which marked almost as great a transformation in 

 our views of variation and displayed the whole evolu- 

 tion problem in a new light. In the era that followed, 

 the study of heredity quickly became not onlv an 

 experimental, but almost an exact science, fairly com- 

 parable to chemistry in its systematic employment of 

 qualitative and quantitative anah'sis, synthesis, pre- 

 diction, and verification. More and more clearly it 

 became evident that the phenomena of heredity are 

 manifestations of definite mechanism in the living 

 body. Microscopical studies on the germ-cells made 

 known an important part of this mechanism and pro- 

 vided us with a simple mechanical explanation of 

 Mendel's law. And suddenly, in the midst of all this, 

 by a kaleidoscopic turn, the fundamental problem of 

 organic evolution crystallises before our eyes into a 

 new form that seems to turn all our previous concep- 

 tions topsy-turvy. 



I will comment briefly on this latest view of evolu- 

 tion, partly because of its inherent interest, but also 

 because it again exemplifies, as in the case of em- 

 bnology, that temptation to wander off into meta- 

 physics {sit venia verho!) which seems so often to be 

 engendered by new and telling discoveries in science. 

 The fundamental question which it raises shows an 

 interesting analogy to that encountered in the study of 

 embn.-ology, and may conveniently be approached from 

 this side. 



To judge by its external aspects, individual employ- 

 ment, like evolution, w-ould seem to proceed from the 

 simple to the complex ; but is this true when we con- 

 sider its inner or essential nature? The egg appears 

 to the eye far simpler than the adult ; yet genetic 

 experiment seems continually to accumulate evidence 

 that for each independent hereditary trait of the 

 adult the egg contains a corresponding something 

 (we know not what) that grows, divides, and is trans- 

 mitted by cell-division without loss of its specific char- 

 acter and independently of other somethings of like 

 order. Thus arises what I will call the puzzle of the 

 microcosm. Is the appearance of simplicity in the egg 

 illusory? Is the hen's egg fundamentally as complex 

 as the hen, and is development merely the trans- 

 formation of one kind of complexity' into another? 

 Such is the ultimate question of ontogeny, which in 

 one form or another has been debated by embr^'ologists 

 for more than two centuries. We stilf cannot answer 

 it. If we attempt to do so, each replies according 

 to the dictates of his individual temperament — that is 



NO. 2560. VOL. QJ.1 



to say, he resorts to some kind of symbolism ; and he 

 still remains free to choose that particular form which 

 he finds most convenient, provided it does not stand 

 in the way of practical efforts to advance our real 

 knowledge through observation and experiment. 

 Those who must have everything reduced to hard and 

 fast formulas will no doubt find this rather disconcert- 

 ing; but worse is to follow. Genetic research now 

 confronts us with essentially the same question as 

 applied to the evolutionary germ. The puzzle of the 

 microcosm has become that of the macrocosm. Were 

 the primitive forms of life really simpler than their 

 apparently more complex descendants? Has organic 

 evolution been from the simple to the complex, or only 

 from one kind of complexity to another? May it 

 even have been from the complex to the simple by 

 successive losses of inhibiting factors w-hich, as they 

 disappear, set free qualities previously held in check? 

 The last of these is the startling question that the 

 president of the British Association propounds in his 

 recent brilliant address at Melbourne, asking us seri- 

 ously to open our minds to the inquiry : " Whether 

 evolution can at all reasonably be represented as an 

 unpacking of an original complex which contained 

 within itself the whole range of complexity which 

 living things exhibit?" This conception, manifestly, 

 is nearly akin to the theory of pangenesis and indi- 

 vidual development, as elaborated especially by De 

 Vries and by Weismann. It inevitably recalls also, if 

 less directly. Bonnet's vision of "palingenesis," which 

 dates from the eighteenth century-. 



W'e should be grateful to those who help us to open 

 our minds ; and Prof. Bateson, as is his wont, performs 

 this difficult operation in so large and masterly a 

 fashion as to command our lively admiration. It 

 must be said of his picturesque and vigorous discussion 

 that we are kept guessing how far we are expected 

 to take it seriously, or at least literally. We have 

 always a lurking suspicion that possibly his main 

 purpose may, after all, be to remind us, by an object- 

 lesson, how far we still are from comprehending the 

 nature and causes of evolution, and this suspicion 

 is strengthened by the explicit statement in a subse- 

 quent address, delivered at Sydney, that our know- 

 ledge of the nature of life is "altogether too slender 

 to warrant speculation on these fundamental ques- 

 tions." Let us, however, assume that we are seriously 

 asked to go further and to enter the cul de sac that 

 Prof. Bateson so invitingly places in our way. Once 

 within it, evidently we are stalemated in respect to 

 the origin and early history of life ; but as to that, one 

 form of total ignorance is perhaps as good as another, 

 and we can still work out how the game has been 

 played, even though we can never find out how the 

 pieces were set up. But has the day so soon arrived 

 when we must resign ourselves to such an ending? 

 Are we prepared to stake so much upon the correct- 

 ness of a single hypothesis of allelomorphism and 

 dominance? This hypothesis — that of "presence and 

 absence " — has undoubtedly been a potent instrument 

 of investigation ; but there are some competent 

 students of genetics who seem to find it equally simple 

 to formulate and analyse the phenomena by the use 

 of a quite different hv-pothesis, and one that involves 

 no such paradoxical consequences in respect to the 

 nature of evolution. Are we not then invited to 

 strain at a gnat and to swallow a camel? 



But I pass over the technical basis of the conception 

 in order to look more broadly at its theoretic super- 

 structure. Is not this, once again, a kind of symbol- 

 ism by which the endeavour is made to deal with a 

 problem that is for the present out of our reach? • 

 Neither you nor I, I dare say, will hesitate to maintain 

 that the primordial Amoeba, if we may so dub the 



