320 Report S.A.A. Advancement of Science. 



mav perhaps call Herbert Spencer's i)riiiciple of equilibration lo 

 the phenomena of heredity and development. 



In order to develope the argument in a logical manner I })ropose 

 to divide the subject matter into the following sectinns: 



(i) The stimulating influence of the environment uijon the individual 

 organism, and the principle of direct equilit)ration between the 

 organism and its environment. 



{2) The pt)ssibililv of stimuli l)eing stored uji in the organism so 

 as to produce after effects, and the inheritance of acquired 

 characters. 



(3) The nature of the ai>paratus b\ which stimuli are stored within 

 the organism, and the principle of equilibration between the 

 cell and its nucleus. 



(4) The germ-cells viewed as store-houses of stimuli, and the principle 

 of equilibration l)etween the soma and the germ-cells. 



(5) The interpretation of ontogeny as a process of progressive 

 equilif>ration, and the biogenetic law. 



(6) Amjihimixis or sexual reproduction. 



I. THE STIMULATING INFLUENCE OF THE ENVIRON- 

 MENT UPON THE INDIVIDUAL ORGANISM AND 

 THE PRINCIPLE OF DIRECT EQUILIBRATION. 



It is perhaps hardly necessary to point out that any individual 

 organism must be in a .state of equilibrium with its environment and 

 that any change in the environment may, if sufficiently long 

 continued, act as a stimulus upon the organism and cause a definite 

 response to be made by the latter. " Direct equilibration in organisms," 

 says Herbert Spencer, " with all its accompanying structural altera- 

 tions, is as certain as is that universal ]>rogress towards equilibrium 

 of which it forms part." 



Examples of such direct equilibration, or modificati(jn of the 

 organism in accordance with change of environment, are familiar to 

 every gardener. A hardy outdoor plant grown in a hothouse may 

 altogether alter its habit of growth. Potatoes allowed to sprout in 

 the dark send out shoots of quite a dififereiit character from those 

 which are produced under normal circumstances. Certain Alpine 

 plants which are especially adapted in their habit to the rigours of 

 an Alpine climate, may be induced to change their mode of growth 

 by simply removing them to sufficientiv warm and sheltered situa- 

 tions, in which their habit ap|)roaches that of their lowland relatives. 



These phenomona are more noticeable in plants than in animals 

 l>ecause plants are constantly making new growth and it is chieflv 

 in the development of new organs or parts that the stimulus of 

 changed environment can produce the corresponding effect. In the 



