284 A THEORY OF HEREDITY VIII 



logical units " plastidules," a name which Haeckel has 

 accepted, and which may very possibly be found per- 

 manently useful. But Elsberg does not appear to 

 have helped on the discussion of the subject to a great 

 extent, since he proceeds no further than is implied 

 in adoj)ting Mr. Darwin's theory of Pangenesis, whilst 

 substituting the "plastidules" for Mr. Darwin s 

 "gemmules." It appears tome that Elsberg in his 

 combination of the Spencerian and Darwinian hypo- 

 theses, has omitted the sound element in the latter, 

 and retained the more questionable. He should have 

 conjoined Mr. Herbert Spencer's conception of '' plasti- 

 dules " — possessing special polarities or force affections 

 which they are capable of propagating as changes of 

 state (i.e. force-waves) to associated plastidules, and 

 so to offspring — with Mr. Darwin's conception of a 

 universal and continuous emission of such changes 

 from all the cells of an organism, and the frequent 

 occurrence of a persistently latent condition of those 

 changes — a condition which Hering's happy use of 

 the term " memory " enables us to illustrate by the 

 analogous (or we should rather say identical) " latent " 

 or '^ dormant condition " of mental impressions. 



This is, in fact, the position which Professor Haeckel 

 takes up — though independently of what Mr. Spencer 

 has written on the subject, excepting so far as the 

 influence of the latter is to be traced in Elsberg's 

 essay. For Haeckel, living matter, protoplasm, or 

 plasson consists of definite molecules — the plastidules 

 — which cannot be divided into smaller plastidules, 

 but can only be split into lower chemical compounds. 



