PRESIDENTIAL ADDRESS. 29 



dules or plasma-molecules, and these are ' probably sur 

 rounded by aqueous envelops ; the greater or less thickness 

 of these aqueous envelops, which at once separate and bind 

 the neighboring plastidules, determines the softer or harder 

 condition of the flowing plasson' (p. 48). 



' Heredity is the transmission of plastidule motion, whereas 

 adaptation is change of plastidule motion' (p. 55). This 

 motion may in its general aspects be conceived as a ramified 

 wave-motion. In all protists or unicellular organisms (proto- 

 phytes and protozoans) this periodical movement of the mass 

 goes on in a correspondingly simple manner while in all 

 tissue-bearing or multicellular creatures (metaphytes and 

 metazoans) it is combined with a mutual generation of the 

 plastids and a division of labor of the plastidules." 



It will be observed that although this theory of heredity 

 lays special stress upon the idea of motion, thereby recogniz 

 ing the element of force, it is nevertheless based like all others 

 upon the existence of ultimate material elements different on 

 the one hand from the chemical molecules and on the other 

 from cells, and intermediate between these. The gemmule of 

 Darwin, the physiological unit of Spencer, and the plastidule 

 of Haeckel are the same in essence, and the study of the phe 

 nomena of these ultimate elements of biology open up a new 

 and most promising field of research into which scarcely any 

 investigator has as yet deliberately entered. 



We are now prepared to consider the objections of Galton 

 and Weismann to the doctrine of the transmission of function 

 ally acquired characters. 



VIEWS OF MR. GAI/TON. 



The earliest expression of Mr. Galton' s views, so far as I 

 am aware, is contained in a paper " On Blood-Relationship " 



