TRANSACTIONS OF SECTION D. 773 



sion of the organic world compared with the elasticity potentially inherent in the 

 reproductive capacities of its members. The more restricted range of particular 

 groups is due to their more special needs, as well as to the necessarily more 

 numerous obstacles encountered ; the total aggregate having to strive only against 

 the resistances and encroachments of inorganic nature, whereas each component part 

 has also to contend with the competition and assaults of distinct congeners. Not 

 only the extent but also the configuration of organic distribution is determined 

 by the manner in which the inward expansive and outward repressive forces 

 counteract or overcome each other at their several places of collision. At some 

 points, from diminution of sustenance, increase of enemies or competitors, or from 

 other adverse circumstances, expansion may be checked or contracted, while at 

 other points, from opposite causes, it may be permitted to an unusual extent, thus 

 leading to frequent or perpetual oscillations of outline, varying on different 

 occasions, but always being a resultant of conflicts between centrifugally expand- 

 ing and centripetally compressing forces. 



Though not so obvious, it is no less conclusive that individual morphology, in 

 like manner, invariably results from the efforts of intrinsic or developmental 

 energies against extrinsic or envelopmental restraints and encroachments. A 

 homogeneous unit expanding centrifugally from a single point, with equal intensity 

 in every direction, amidst an unresisting or uniformly resisting medium would 

 retain an absolutely spherical figure, its magnitude being a resultant of the equili- 

 brium between internal tension and external resistances ; any deviation from its 

 original symmetry indicating a corresponding degree of inequality between 

 mutually opposing inward and outward forces at their several points of contact. 

 Such a unicentral expanding system would have no internal conflicts, all the 

 obstacles to its evolutional tendencies being purely of external origin ; but a multi- 

 central or composite body, such as every complex organism represents, including 

 many distinct simultaneously evolving parts, must necessarily be the subject of 

 interior as well as exterior conditions of restraint, not only its total bulk and 

 shape, but also the confirmation and relative position of different organs, as well 

 as the localisation and composition of every tissue element, being consequences of 

 equilibria between innumerable developmental tensions and envelopmental restraints, 

 any modification in such an economy (wherever occurring and however induced) 

 possibly reverberating so as to effect its entire constitution. Every complete germ 

 at its inception contains a certain specific potentiality or developmental capacity, 

 which, under an optimism of conditions would evolve a maximum of normal 

 results. 



The different cells in this incipient economy constitute a number of distinct 

 centres of latent or potential elasticity, which, by nutrition, become separate foci 

 of mutually conflicting expansive energies. In such an interdependent arrange- 

 ment some parts may be unduly favoured and developed at the expense of incor 

 porated elements, yet in no possible way can any structure be made to evolve more 

 than was potentially included in its primitive organisation, for, while accessory 

 provisions are indispensable to development, these possess only a stimulative or 

 permissive value, never a creative power; their share in the process consisting in 

 the liberation and determination of previously occluded inherent potentialities. 



Hence, when some new character is evolved or an old one modified (whether 

 abruptly in a single individual or gradually through a succession of generations 

 does not alter the case, genealogical attainments being never more than the sum cr 

 resultant of individual acquirements), this does not imply that such has been 

 directly annexed, or introduced ab extra, but rather indicates that some unusual 

 facility has been afforded, or some previously imposed restraint relaxed ; the com- 

 munication of new facilities and the withdrawal of former restraints being equiva- 

 lent expressions. 



The mere association, however, of developmental impulses and envelopmental 

 restraints could never issue in any definite progressive results unless subjected to the 

 determination of some controlling mechanism of order, so that the regularity, 

 definiteness, and consistency observable in organic reactions and relations, testify to 

 theadditionalexister.ee and jurisdiction of a supplementary principle of co-ordinativa 



