108 THE EVOLUTION THEOKY 



strength of memory that the states of these brain-cells should be 

 communicated by the telegraphic path of the nerve-cells to the 

 germ-cells, and should there modify only the determinants of the 

 brain-cells, and should do so in such a way that, in the subsequent 

 development of an embryo from the germ-cell, the corresponding 

 brain- cells should turn out to be capable of increased functional 

 activity. But as the determinants are not miniature brain-cells, but 

 only groups of biophors of unknown constitution, and are assuredly 

 different from those cells ; as they are not ' seed-grains ' of the brain- 

 cells, but only living germ-units which, in co-operation with the rest 

 exercise a decisive influence on the memory-cells of the brain, I can only 

 compare the assumption of the transmission of the results of memory- 

 exercise to the telegraphing of a poem, which is handed in in German, 

 but at the place of arrival appears on the paper translated into 

 Chinese. 



Nevertheless, as I have said before, I do not disagree with those 

 who say, with Oscar Hertwig, that the impossibility of forming 

 a conception of the physiological nexus involved in the assumed 

 transmission does not ijjso facto constrain us to conclude that the 

 transmission does not occur. I cannot, however, agree with Hertwig 

 that the case is exactly the same as in the ' converse process,' that is, 

 'in the development of the given invisible primary constituents in 

 the inheritance of the cell into the visible characters of the personal 

 part.' Certainly no one can state with any definiteness how the germ 

 goes to work, so that from it there arises an eye or a brain with its 

 millionfold intricacies of nerve-paths, but although the process cannot 

 be understood in detail, it can in principle, and this is just what 

 is impossible in regard to the communication of functional modifica- 

 tions to the germ. Moreover, in addition to this, there is the very 

 important difference that, in the one case, we know with certainty 

 that the process actually takes place, although we cannot understand 

 its mechanical sequence in detail, while in the other we cannot even 

 prove that the supposed process is a real one at all. From the 

 fact that we are unable to form clear conceptions of a hypothetical 

 process, we are not justified, it seems to me, in assuming it to be real, 

 even though we are aware of many other processes in nature which 

 we are unable to understand. 



Nor does Hertwig take up this position, for he is at pains to 

 show the mechanical possibility of the process of inheritance which 

 he assumes, and he bases this upon the suggestions made by Hering 

 in his famous work Ueber das Geddchtnus ah eine aUgemeine 

 Function der organisirten Materie [On meniory as a genercd 



