608 RICHARD GOLDSCHMIDT 



slightly. But occasionally one cross gives aberrant results. For 

 example, we have made the cross of the two races which gives 

 nothing but males some dozen times with identical results. 

 Once only there were three extremely intersexual females, rep- 

 resenting some minus individuals of a range of variation. This, 

 and similar facts from other crosses, poiats strongly to a quan- 

 titative variation of the factor-enzymes in the gametes, the oc- 

 casional extreme departures from the typical results being due 

 to the union, in fertilization, of a minus value for one, and a 

 plus value for the other enzyme. 



Vll 



One of the important advances which recent genetic research 

 has made is to furnish proof for the fact that the distribution of 

 the chromosomes, especially the sex-chromosomes, and the 

 S3rmbolistic conceptions about the behaviour of Mendelian factors 

 are one and the same thing. Thus the step from a symbolistic 

 representation of a mechanism to the real disclosure of the mech- 

 anism has been made. We have tried in this paper to advance 

 still further, namely, to a realization of what is moved by the 

 mechanism and why. Do these conceptions fit the facts of 

 cytology? We have briefly discussed that question in another 

 place in connection with other questions, but wish again briefly 

 to indicate the chief problem. We cannot conceive the chro- 

 mosomes as built up from chromatin particles, which are them- 

 selves the chemical substratum of heredity. We believe that 

 chromatin is a skeleton substance which works as an adsorbens 

 for the enzymes, which really constitute the chemical basis of 

 heredit}^ We have now seen how important the quantitative 

 behavior of these enzjmies is for the process of heredity. The 

 quantity of adsorption of an enzyme by an adsorbens depends 

 upon the qualities of both and the surface of the adsorbens. The 

 wonderful uniformity of size and shape of the chromosomes of a 

 given animal appears, therefore, as a minute mechanism to 

 guarantee the typical quantity of enzymes of heredity to be as- 

 sembled at the moment of fertilization. And all the strange 

 processes preceding the maturation of the sex-cells appear- 



