2l8 



NA TURE 



[July 9, 1896 



organs the old cells are gradually worn out and replaced 

 by new ones. The cells of the formative layer (such as 

 the Malpighian layer of the epidermis) will not be pre- 

 cisely equal in their qualities, and those whose assimi- 

 lation and reproduction is furthered by the "functional 

 stimuli " (that is, the stimuli, such as light, contact, 

 chemical action, which call forth the performance of the 

 function of the organ as a response) will flourish at the 

 expense of others. The same argument is only capable 

 of a limited application to the case of organs, since 

 different organs fulfil dififerent functions, and one function 

 cannot preponderate at the e.xpense of another without 

 upsetting that balance which is essential to the con- 

 tinuance of life. Nevertheless, that there is some such 

 tendency is shown by the fact that if an organ ceases to 

 perform its function properly (such as occurs, for instance, 

 in the case of the kidney in 15right's disease), it is apt to 

 be pressed upon, and eventually destroyed by, the 

 hypertrophied connective tissue. 



It will thus be seen that Prof. Roux's theory, which 

 he calls "the Conflict of the Parts within the organism," 

 is anew explanation of the well-known effects of use and 

 disuse. He points out that it completely difliers from the 

 crude mechanical hypothesis put forward by Herbert 

 Spencer in his " Principles of Biology" ; this latter, dis. 

 tinguished by Rou.x as the theory of " Functional Con- 

 gestion," attributed increase in bulk, due to use, to the 

 increased blood-supply mechanically brought about by in- 

 creased function. Apart from the fact that increase in bulk 

 in an organ only takes place in those dimensions in which 

 it is called for by its function (thus the epidermis increases 

 in thickness, a muscle in breadth, &c.), whereas increased 

 blood-supply should cause uniform increase in all dimen- 

 sions, Herbert Spencer's theory is inconsistent with the 

 fact that if the nerves which convey the ordinary stimuli 

 to an organ (such as a salivary gland) are cut, we may 

 have congestion accompanied by degeneration, rather 

 than increase in size. 



It must be confessed that there is much about Prof 

 Roux's theory which induces one to wish that it were 

 true. Apart, however, from the minor circumstance that 

 the assumption of competing parts within the cell is an 

 absolutely unsupported hypothesis, this theory utterly 

 breaks down when we come to consider the question of 

 heredity. Let it be granted that the liver consists of 

 several kinds of cell, some of which perform their function 

 better than others, and thus survive — how are these 

 survivors to impress their peculiarities on that portion 

 of the ovum which is destined to produce the liver in the 

 young animal? It seems to us that before the question 

 of " direct functional adaptation " can be even entertained 

 by zoologists the question of the possibility of the in- 

 heritance of acc|uired variations must be grappled with, 

 and decided one way or the other. 



Prof Roux next passes on to some general considera- 

 tions on the nature of life and the origin of life and con- 

 sciousness ; he points out that life is not capable of being 

 statically defined ; it is, he says, essentially a process, not 

 a series of chemical attributes, and hence it is absurd to 

 suppose that a slight chemical difference is all we have 

 to assume, in order to account for the difference in pro- 

 perties of living and dead protoplasm. The speculations 

 as to the origin of life and consciousness are as fatuous as 

 NO. 1393, VOL. 54J 



such theorising usually is, and we think that a little study 

 of elementary psychology would have prevented Prof. 

 Roux giving vent to his extraordinary ideas as to the 

 origin of consciousness. 



The remaining papers in the first volume deal chiefly 

 with special cases in which Prof Roux has elucidated 

 the wonderful functional adaptation which is seen not 

 only in the finest details of structure (such as the arrange- 

 ment of the connective tissue in the tail-fin of the 

 dolphin), but also in the makeshifts which the organism 

 produces to make up for injuries to its original structure 

 (as, for instance, the structure of the bone in the case of 

 knee anchylosis). 



The huge second volume is devoted to the subject of 

 the " Mechanics of Development," of which study Prof. 

 Roux may, as we have said before, be regarded as the 

 founder. A considerable portion of the volume is taken 

 up with replies to the successive publications of Driesch 

 and Hertwig, who have pursued this branch of zoology 

 with such brilliant success. Prof Roux has only himself 

 to thank if more attention is paid to the publications of 

 these observers than to his work ; for he has carried in 

 this subject theorising and prolixity to an intolerable 

 excess. The main difference between Driesch and 

 Hertwig on the one hand, and Roux on the other, may 

 be briefly stated : the former maintain that in the 

 segmentation of the egg, we have a process which is 

 essentially a mere multiplication of nuclei, all of which 

 are similar to each other ; the relative position of these 

 nuclei determines what organs of the body they will 

 eventually help to form ; if their relative positions are 

 altered by pressure or other mechanical means, their 

 respective fates will be altered ; or if one of the first 

 eight segments of the ^■gg be separated from all the rest, 

 it is still able to form all the organs of the adult. Roux, 

 on the other hand, maintains that by the formation of 

 the first four segments of the frog's ^%%, the materials 

 which are capable of differentiating themselves into the 

 right and left sides and anterior and posterior halves of 

 the animal are separated from each other, and that if 

 one of the first two segments of the egg be severely 

 injured, the other will develop into a half blastula, and 

 eventually a half gastrula, and even further ; the missing 

 half will, however, be regenerated by the " reanimation " 

 of the wounded blastomere by the migration of nuclei 

 from the developed side. 



It is of course extremely probable that in the normal 

 course of development, the first segmentation furrow may 

 coincide with the future long axis of the embryo, and if 

 this is the case, the second furrow being at right angles to 

 the first, will necessarily divide the egg into halves, one of 

 which will be anterior and the other posterior. The ques- 

 tion, however, whether this coincidence is essential or 

 accidental, can only be settled by forcing the e.%% into such 

 positions that the direction of the furrows dividing the 

 segments is altered, and then observing whether the 

 developmental history undergoes a corresponding altera- 

 tion. Driesch and Hertwig have done this, and laid a 

 strong foundation for their view, that the segmentation 

 nuclei can be shaken together like a bag of balls, and still 

 normal development ensue ; and in the case of echino- 

 derms and amphioxus, their theory, it seems to us, has 

 been proved up to the hilt. Hertwig has written also a 



