288 ON THE INTERNAL FORM [ch. 



little value of its own. That a given cell, an ovum for instance, 

 contains this or that visible substance or structure, germinal vesicle 

 or germinal spot, chromatin or achromatin, chromosomes or centro- 

 somes, obviously gives no explanation of the activities of the cell. 

 And in all such hypotheses as that of "pangenesis," in all the 

 theories which attribute specific properties to micellae, chromosomes, 

 idioplasts, ids, or other constituent particles of protoplasm or of 

 the cell, we are apt to fall into the error of attributing to matter 

 what is due to energy and is manifested in force: or, more strictly 

 speaking, of attributing to material particles individually what is 

 due to the energy of their collocation. 



The tendency is a very natural one, as knowledge of structure 

 increases, to ascribe particular virtues to the material structures 

 themselves, and the error is one into which the disciple is Ukely 

 to fall but "of which we need not suspect the master-mind. The 

 dynamical aspect of the case was in all probability kept well in view 

 by those who, Hke Goodsir himself, first attacked the problem of 

 the cell and originated our conceptions of its nature and functions*. 



If we speak, as Weismann and others speak, of an "hereditary 

 sitbstance,'' a substance which is spHt off from the parent-body, and 

 which hands on to the new generation the characteristics of the old, 

 we can only justify our mode of speech by the assumption that that 

 particular portion of matter is the essential vehicle of a particular 

 charge or distribution of energy, in which is involved the capabihty 

 of producing motion, or of doing "work." For, as Newton said, 

 to tell us that a thing "is endowed with an occult specific quahtyf, 

 by which it acts and produces manifest effects, is to tell us nothing ; 

 but to derive two or three general principles of motion { from 



* See also {int. al.) R. S. Lillie's papers on the physiology of cell-division in the 

 Journ. Exper. Physiology; especially No. vi, Rhythmical changes in the resistance 

 of the dividing sea-urchin egg, ibid, xvi, pp. 369-402, 1916. 



f Such as the vertu donnitive which accounts for the soporific action of opium. 

 We are now more apt. as Le Dantec says, to substitute for this occult quality the 

 hypothetical substance dormitin. 



X This is the old philosophic axiom writ large: Ignorato motu, ignoratur -natura; 

 which again is but an adaptation of Aristotle's phrase, 17 dpx^ ^V^ Kivrjcrecxjs, as 

 equivalent to the "Efiicient Cause." FitzGerald holds that "all explanation 

 consists in a description of underlying motions" {Scientific Writings, 1902, p. 385); 

 and Oliver Lodge remarked, "You can move Matter; it is the only thing you can 

 do to it." 



