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SCIENCE 



tN. S. Vol. XXVIII. No. 717 



He supposes that adaptive, in contradis- 

 tinction to organic, characters are produced 

 by external causes; and since these char- 

 acters are hereditary there must be com- 

 munication between the seat of adaptation 

 and the germ-cells. This telegraphic effect 

 is supposed to be effected by the network 

 of idioplasm which traverses the body, in 

 the case of plants by the intercellular proto- 

 plasmic threads. 



Semon faces the difficulty boldly. "When 

 a new character appears in the body of an 

 organism, in response to changing environ- 

 ment, Semon assumes that a new engram is 

 added to the nuclei in the part affected; 

 and that, further, the disturbance tends to 

 spread to all the nuclei of the body (in- 

 cluding those of the germ-cells), and to 

 produce in them the same change. In 

 plants the flow must be conceived as travel- 

 ing by intercellular plasmic threads, but in 

 animals primarily by nerve-trunks. Thus 

 the reproductive elements must be consid- 

 ered 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 effi- 

 cient 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 



" Weismann, " The Evolution Tlieory," 1904, 

 Vol. II., p. 63 ; also his " Richard Semen's 

 ' Iilneme ' und die Vererbung erworbener Eigen- 

 schaften," in the ArcMv fur Rassen- und Gesell- 

 schafts-Biologie, 1906. Semon has replied in the 

 same journal for 1907. 



only differ from each other in intensity, 

 and therefore there can be no communica- 

 tion of potentialities to the germ-cell. He 

 holds it to be impossible that somatic 

 changes should be telegraphed to the germ- 

 cell and be reproduced 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 radi- 

 ating influence will produce the same 

 effect on all the nuclei of the organism. 

 My own point of view is the following. In 

 a plant ,(as already pointed out) the ecto- 

 plasm 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 ectoplasm 

 threads the primary excitation will spread 

 and produce in other cells a faint copy of 

 the engram impressed on the somatic cells 

 originally stimulated. But in all these as- 

 sumptions we are met by the question to 

 which Weismann has called attention — 

 namely, whether nervous impulses can 

 differ from one another in quality V^ The 

 general opinion of physiologists is un- 

 doubtedly to the opposite effect— namely, 

 that all nervous impulses are identical in 

 quality. But there are notable exceptions, 

 for instance, Hering,^* who strongly sup- 

 ports what may be called the qualitative 

 theory. I am not competent to form an 

 opinion on the subject, but I confess to 

 being impressed by Hering's argument 



" 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 con- 

 tain mere fragments of the nucleus. 



" I use this word in the ordinary sense without 

 reference to what is known as modality. 



" " Zur Theorie der Nerventhatigkeit, Akad- 

 emische Vortrag," 1898 (Veit, Leipzig). 



