NATURE 



505 



THURSDAY, SEPTEMBER 29, 1881 



THE STRUGGLE OF PARTS IN THE 

 ORGANISM 



Der Kainpf der Theile im Orgaiiisnms : ein Beiirag znr 

 'Vervollstiindigung der mechanischen ZweckmdssigkeiU- 

 leln-e. Von Dr. Wilhelm Roux, Privatdocent und 

 Assistant am Anatomischen Institut zu Breslau. 

 (Leipzig : Wilhelm Engelmann, 1881.) 



SINCE the first dawn of methodical inquiry one of the 

 largest and most important problems that has 

 always been presented to scientific thought is the explana- 

 tion of the endless number and complex variety of those 

 apparently purposive adaptations of structures to functions 

 which are everywhere to be met with in organic nature. 

 Until within the last few years the solution of this problem 

 was all but universally sought in the hypothesis of a de- 

 signing mind, and as no other cause had been suggested 

 as adequate to produce such a multitude of seemingly 

 teleological effects, it became a habit of philosophical 

 thinking to regard these effects as evidences of a creating 

 intelligence. And although the scientific instincts of an 

 individual here and there pointed towards the belief that 

 in some unaccountable manner the facts were due to 

 physical as distinguished from metaphysical causes, the 

 scientific instincts which pointed in this direction were 

 unable to justify themselves on grounds of reason, inas- 

 much as they were unable to suggest any non-mental 

 principle which could reasonably be taken to explain a 

 class of phenomena bearing so suggestively the appear- 

 ance of a mental origin. The tide of thought in this 

 matter therefore rose without interruption or perceptible 

 hindrance in the direction of supernaturalism, until it 

 attained its highest level in the " Argument from Design " 

 as elaborated by the natural theologians of the past gene- 

 ration. Then with a suddenness only less surprising than 

 its completeness the end came ; the fountains of this 

 great deep were broken up by the power of one man, and 

 never in the history of thought has a change been effected 

 of a comparable magnitude or importance. 



But although the theory of n.itural selection as con- 

 ceived and elaborated by Mr. Darwin so completely sub- 

 verted the foundations of what may be termed a scientific 

 teleology, it soon became apparent that natural selection 

 alone was not adequate to explain all the facts of adapta- 

 tion that are met with in organic nature. Not to enter 

 upon the question, which we can only hope that future 

 generations may be able to answer, as to how far natural 

 selection alone, or unassisted by any other principle, is 

 competent to produce changes of specific type— how far 

 in other words, we are to attribute the evolution of species 

 to the uncompounded operation of the survival of the 

 fittest, and how far to the probable operation of other and 

 unknown factors — not to enter upon this question, it is 

 enough to observe that many cases of adaptation which 

 occur in the part; of individual organisms cannot possibly 

 be explained by the theory of natural selection as this is 

 applied to explain cases of adaptation which are presented 

 by specific types. Thus, to take the most simple illustra- 

 tion, the effects of use and of disuse in increasing or 

 diminishing the functional utility of an organ in obvious 

 Vol. xxiv. — No. 622 



adaptation to the requirements of the individual organism 

 — these effects clearly cannot be attributed to survival of 

 the fittest organisms. Similarly in the morbid processes 

 of disease there is frequently observed "an effort of 

 nature " to throw off the affected part, or otherwise to 

 effect a spontaneous cure. These and other considera- 

 tions of the same kind have led all the more thoughtful 

 evolutionists— including Mr. Darwin himself— to conclude 

 that over and above the gieat principle of natural selec- 

 tion, operating from without the organism and therefore 

 called by Mr. Herbert Spencer " indirect equilibration," 

 there must be other principles of an adaptive character 

 at work within the organism itself, and therefore collec- 

 tively called by Mr. Spencer the principles of "direct 

 equilibration." And it is evident that one of the most 

 important problems now presented to evolutionists is that 

 of ascertaining what are these principles of direct equili- 

 bration. The work before us is an interesting effort in 

 this direction. 



The idea which Dr. Roux elaborates at much length 

 is that the principle of the struggle for existence and 

 consequent survival of the fittest is in active oper- 

 ation, not only as between individuals of the same or 

 different species, but also between the constituent parts 

 of the same individual. As all the parts of an or- 

 ganism receive their nourishment from a common and 

 limited supply, there necessarily arises among them a 

 competition for food, so that, for instance, in any cellulai 

 structure the most vigorous cells will survive by starving 

 out the less vigorous, just as is the case with organisms 

 living in an area of limited food-supply. Also, and 

 especially after the period of full growth of the organism 

 has been attained, the mutual pressure exerted by neigh- 

 bouring cells must give rise to a further competition — a 

 struggle for room or space wherein to develop — and here 

 again it will be the most favoured elements that will be 

 successful in attaining a vigorous maturity. In these and 

 in several other minor respects which we need not wait to 

 m.ention. Dr. Roux maintains that all the organs, cells, 

 and even molecular groupings of an organism are so 

 situated as to be constantly under the evolutionary influ- 

 ence of the struggle for existence. If such is granted to 

 be the case, the author proceeds to show how a foundation 

 is supplied for explaining all or many cases of "direct 

 equilibration," or, as he terms it, " capacity of functional 

 adaptation." For this capacity amounts merely to an 

 increase or diminution of the functional power of a part 

 under the influence of an increase or diminution of 

 stimulus, using the latter term in its most comprehensive 

 signification as including any change of conditions acting 

 from without. (This, at least, seems to be the sense in 

 which Dr. Roux uses the term, as he applies it indif- 

 ferently to an excitation of nerve or muscle, increase of 

 traction upon a bone, blood-pressure in an artery, &c.) 

 But if a stimulus means a change of conditions, it means, 

 when frequently repeated, a change of the physiological 

 environment of the structure affected, and therefore, if the 

 constituent parts of this structure are subject among 

 themselves to a keen struggle for existence, those parts 

 which arc best adapted to the change will survive, while 

 the others will succumb, with the ultimate effect of altering 

 the form or function of the structure so as to meet the 

 new circumstances of stimulation. 



