HEREDITY. 449 



The building energy being thus understood to be a 

 mode of molecular motion, we are not at liberty to 

 suppose that its existence is dependent on the dimen- 

 sions of the organic body which exhibits it. It is as char- 

 acteristic of the organic unit or plastidule as the mode 

 of motion which builds the crystal is of the simplest 

 molecular aggregate from which the crystal arises. 

 Bathmism has, however, no other resemblance to 

 crystalloid cohesion. The latter is a simple energy 

 which acts within geometrically related spaces, with- 

 out regard to anything else but the present compulsion 

 of superior weight-energy. In bathmism we see the 

 resultant of innumerable antecedent influences, which 

 builds an organism constructed for adaptations to the 

 varied and irregularly occurring contingencies which 

 characterize the life of living beings. As this resultant 

 is distinctive for every species, bathmism must be 

 regarded as a generic term, and the characteristic 

 growth-energy of each species as distinct species of 

 energy, which presents also diversities expressive of 

 the peculiarities of individuals. 



The preceding statements do not, of course, con- 

 stitute an explanation of the exact manner in which a 

 stimulus which effects say the contraction of a muscle, 

 effects molecular movements of the nuclei of the re- 

 productive cells. This is a question of organic molec- 

 ular physics, a science which has made scarcely a be- 

 ginning. That the transmission of such influence is 

 through nutritive channels, by the intermediation of a 

 nervous structure where one exists, may be supposed. 

 Poulton's experiments on Lepidoptera, already cited, 

 led him to believe that the effect of color-environment 

 was transmitted to the pigment-cells through the me- 

 dium of the nervous system. That the modus operand! 



