NATURE 



217 



THURSDAY, JULY 9, 1896. 



PROFESSOR ROU.WS COLLECTED WORKS. 



■Gesammelte Abhandlungcn iiber Entvjicklungsmcchanik 

 der Organismcn. \'on Wilhclm Roux. \'ol. i. Pp. 

 xiv + S16. Vol. ii. I'p. iv + 1075, 10 plates and 33 

 woodcuts, (Leipzig: \V. Engelmann, 1895.) 



ALTHOUGH Prof. Roux must be regarded as the 

 founder of that branch of zoological research 

 called " The Mechanics of I^evelopment," which has 

 recently become so popular, yet his works are com- 

 paratively little known to zoologists in this country ; and 

 it will probably occasion a mild shock of surprise to the 

 English reader, to see the two huge tomes which bear 

 Prof Rou.vs name. 



When, however, one peruses these works, it soon 

 becomes clear, from the numerous complaints on the 

 subject which Prof Roux makes, that the writer's own 

 countrj-men have not been in the habit of reading his 

 publications with that care which their imposing size 

 would seem to demand ; and whatever wonder one may 

 feel at this in the first instance, is soon removed when 

 one becomes acquainted with the contents of the volumes. 

 It may be said, we think with truth, that next to the 

 recording of careless observations, the most deadly sin 

 which a zoological writer can commit is prolixity, and it 

 must be confessed that in this respect Prof Roux sins 

 very badly. The quantity of literature which is pouring 

 in on us is stupendous ; it is becoming more and more 

 difficult for a zoologist to keep himself abreast of the 

 times in more than an exceedingly limited department of 

 the subject, and it seems to us that it is the first duty of 

 every writer to put his results as briefly as is consistent 

 with clearness. In justice to Prof Roux, it should be 

 mentioned that there is in this, as in every "complete 

 edition of works," a good deal of unavoidable repetition, 

 since of course the volumes are made up of separate 

 papers, in several of which the same or similar subjects 

 are treated ; but when every allowance has been made, 

 one is obliged to confess that the proportion of theory to 

 fact is enormous, and that no effort is made to put 

 matters in a compact and terse manner. 



The first volume may be said to contain Prof. Roux's 

 theory of organic evolution, as well as several applications 

 of it in specific cases. The proper place to commence 

 the perusal is with the second paper ; the first paper 

 contains an account of the laws of branching of blood- 

 vessels, which laws are regarded by Prof Roux as special 

 instances of the general principles deduced in the second 

 essay from a general sur\cy of biological facts. 



Prof Roux first shows the extreme difficulty of 

 accounting by simple natural selection for the innumer- 

 able adaptations, carried out into the finest detail, which 

 are met with in all the organs of the vertebrate body. Ac- 

 cording to this theor)', a variation, in order to be preserved, 

 must be of such decided advantage or disadvantage to 

 its possessor as to settle the question of survival. When 

 we find, however, that all over the body secondary blood- 

 vessels are given off at such angles that the blood- 

 NO. 1393, VOL. 54] 



current encounters no frictional resistance, that in bones 

 the meshes of the spongy ossification are disposed so as 

 to strengthen the structure only in those directions in 

 which it is apt to be bent, and thus effect the maximum 

 of economy consistent with efficiency ; that the fibres of 

 fasciae are arranged parallel to the directions of tension ; 

 how are we to picture to ourselves such arrangements 

 arising from the accumulation of irregular variations ? 

 Are we seriously asked to believe that a slight alteration 

 in the direction of the fibres of one of the tendons, or in 

 the angle which a small artery makes with the larger one 

 from which it springs, would determine the survival of an 

 individual ? Is it credible that animals are so tre- 

 mendously hard-pressed for food that such a trifling 

 economy in material would appreciably affect them ? 

 Even if we are capable of such confiding faith in the 

 theory, we are met by further difficulties. Suppose, for 

 e.xample, that a better arrangement of the skeletal 

 material in a given bone will save the life of an animal, 

 what right have we to assume that this va.riation will be 

 accompanied by similar advantageous changes in other 

 organs ? Are not the chances a thousand to one, that 

 the advantage which one animal possesses in one organ 

 will be balanced by the advantages which another 

 possesses in another respect, so that natural selection will 

 have no opportunity to heap up variations ? It is to be 

 observed that even if we assume that " related parts " 

 vary together, it will help us. For the question s not one 

 of a general change in the character of bones, for 

 instance, all over the body, but of the special adaptation 

 of each bone to the local needs. Further, if we say that 

 at one period in the existence of vertebrates, one organ 

 was of relatively great importance and improved by 

 natural selection, and then another, how are we to 

 suppose that the change from an aquatic to an air- 

 breathing existence took place ? Here, as Prof. Roux 

 points out, we must have had simultaneous modifications 

 in almost all the organs of the body : the respiratory and 

 circulatory organs, the limb muscles, the eye and other 

 sense organs, must all have changed at the same time. 



It must be admitted that Prof Roux has brought 

 together a most powerful case against the doctrine of the 

 " all-sufficiency of natural selection," and we feel sure 

 that his arguments will awaken a sympathetic chord in 

 the minds of many, if not most, zoologists, amongst 

 whom there is a general feeling that we want something 

 more than natural selection. 



Destructive criticism is, however, always easier than 

 constructive hypothesis, and it seems to us that the 

 hypothesis which Prof Roux puts forward as supple- 

 mentary to the ordinary doctrine of natural selection is 

 not by any means satisfactory. Briefly it is as follows. 

 Every cell, he assumes, is made up of various parts 

 capable of assimilation and reproduction (the biophores 

 of Weismann), and it is infinitely probable that the rates 

 of assimilation and reproduction of these parts will not 

 be alike. Hence those which thrive best under the 

 stimuli which are pouring in upon the cell, will increase 

 faster than the others, and gradually squeeze them out 

 of existence, and by this means the most useful cell 

 qualities will gradually be evolved. The same reasoning 

 applies to the cells themselves. We know that in many 



