24 president's address, 



is given Ijy Rigiiano.' I regret that the space at my command does not 

 permit me to give a full account of his interesting speculation on somatic 

 inheritance. It resembles the theories of Hering, Butler, and Semon in 

 postulating a'quality of living things, which is the basis both of memory 

 and inheritance. But it differs from them in seeking for a physical 

 explanation or model of what is common to the two. He compares the 

 nucleus to an electric accumulator which in its discharge gives out the 

 same sort of energy that it has received. How far this is an allowable 

 parallel I am not prepared to say, and in what follows I have given 

 llignano's results in biological terms. What interests me is the con- 

 clusion that the impulse conveyed to the nucleus of the germ-cell is, as 

 far as results are concerned, the external stimulus. Thus, if a somatic 

 cell (A) is induced by an external stimulus (S) acting on the nucleus to 

 assume a new manner of development, a disturbance spreads through the 

 organism, so that finally the nuclei of the germ-cells are altered in a 

 similar manner. When the cellular descendants of the germ-cells reach 

 the same stage of ontogeny as that in which the original stimulation 

 occurred, a stimulus comes into action equivalent to S as regards the 

 results it is capable of producing. So that the change originally wrought 

 in cell A by the actual stimulus S is now reproduced by what may be 

 called an inherited stimulus. But when A was originally afTected other 

 cells, B, C, T), may have reacted to S by various forms of growth. And 

 therefore when during the development of the altered germ-cell some- 

 thing equivalent to S comes into play, there will be induced, not merely 

 the original change in the development of A, but also the changes which 

 were originally induced in the growth of B, C, D. Thus, according to 

 Rignano, the germ-nucleus releases a number of developmental processes, 

 each of which would, according to Weismann, require a separate deter- 

 minant. 



If the view here given is accepted, we must take a new view of 

 W^eismann's cases of simultaneous stimulation, i.e., cases like Fischer's 

 experiments on Arctia caja, which he does not allow to be somatic 

 inheritance. If we are right in saying that, the original excitation of 

 the soma is transferi-ed to the germ-cell, and it does not matter whether 

 the stimulus is transferred by ' telegraphy,' or whether a given cause, 

 e.g., a low temperature, acts simultaneously on soma and germ-cell. In 

 both cases we have a given alteration produced in the nuclei of the 

 soma and the germ-cell. Nageli used the woi'd telegraph)/ to mean a 

 dynamic form of transference, but he did not exclude the possibility of 

 the same effect being produced by the movement of chemical subistances, 

 and went so far as to suggest that the sieve tubes might convey such 

 stimuli in plants. In any case this point of view - deserves careful 

 consideration. 



' For what is here given I am partly indebted to Signor Rignano's letters, 

 ? Poo Pemon, ArcHr f. Jia^sm- vntl frt'urllsuIinftn-Ti'ioIoqic, 10^7, p. HO. 



