22 president's address. 



Seiiioii faces the dilliculty boldly. When a new cliaraoter appears in 

 the body of an organism, in response to changing environment, Semon 

 assumes that a new engrain is added to the nuclei in the part affected ; 

 and that, further, the disturbance tends to spread to all the nuclei of the 

 body (including those of the germ-cells), and to produce in them the same 

 change. In plants the flow must be conceived as travelling by intercellular 

 plasmic threads, but in animals primarily by nerve-trunks. Thus the 

 reproductive elements must be considered as having in some degree the 

 character of nerve-cells. So that, for instance, if we are to believe that 

 an individual habit may be inherited and appear as an instinct, the 

 repetition of the habit will not merely mean changes in the central nervous 

 .system, but also corresponding changes in the germ-cells. These will be, 

 according to Semon, excessively faint in comparison to the nerve-engrams, 

 and can only be made eflicient by prolonged action. Semon lays great 

 stress on the slowness of the process of building up efficient engrams in 

 the germ- cells. 



Weismann ^ speaks of the impossibility of germinal engrams being 

 formed in this way. He objects that nerve-currents can only differ from 

 each other in intensity, and therefore there can be no communication 

 of potentialities to the germ-cell. He holds it to be impossible that 

 somatic changes should be telegraphed to the germ-cell and be re- 

 produced ontogenetically — a process which he compares to a telegram 

 despatched in German and arriving in Chinese. According to Semon ^ 

 what radiates from the point of stimulation in the soma is the primary 

 excitation set up in the somatic cells ; if this is so, the radiating influence 

 will produce the same effect on all the nuclei of the oi'ganism. My 

 own point of view i^ the following. In a plant (as already pointed out) 

 the ectoplasm may be compared to the sense-organ of the cell, and the 

 primary excitation of the cell will be a change in the ectoplasm ; but 

 since cells are connected by ectoplasmic threads the primary excitation 

 will spread and produce in other cells a faint copy of the engram im- 

 pressed on the somatic cells originally stimulated. But in all these 

 assumptions we are met by the question to which Weismann has called 

 attention — namely, whether nervous impulses can differ from one another 

 in quality 1 ^ The general opinion of physiologists is undoubtedly to the 

 opposite effect — namely, that all nervous impulses are identical in quality. 

 But there are notable exceptions : for instance, Hering,'' who strongly 



' Weismann, The Eoolntion Theory, 1904, vol. ii. p. 63 ; also his Richard Semon'x 

 ^ Afneme ' u/id die Vererhmig ermorhener Elgenschaften,m ihe Archiv fur Jiassen- 

 und Gesellschafts-Biologie, 1906. Semon has replied in the same journal for 1907. 



^ Semon, Mneme, ed. i. p. 142, does not, however, consider it proved that the 

 nucleus is necessarily the smallest element in which the whole inheritance resides. 

 He refers especially to the regeneration of sections of Stentor which contain mere 

 fragments of the nucleus. 



' I use this word in the ordinary sense without reference to what is known as 

 modality. 



* Zwr Thsorie der Nerventhdtigkeit, Akademische Vortrag, 1898 (Veit, Leipzig), 



