50 THE PLAY OF ANIMALS. 



life; but merely seeing these things wakes in him a 

 strong impulse to plunder, hunt, and kill, apparently 

 because his savage ancestors commonly gained their 

 subsistence by such means. There is in him an in- 

 timate causal connection between the sight of cer- 

 tain free animals, or birds' eggs, and the impulse to 

 plunder, slay, and rend. That this was the case 

 with our animal ancestors we are convinced from 

 the life of modern apes, which is sustained principal- 

 ly by means of spoil taken from smaller animals, espe- 

 cially insects, young birds, and birds' eggs." * " Girls, 

 as well as boys, show in their play unmistakable signs 

 of having inherited the characteristic habits of the 

 race."f Thus play becomes the result of intelligent 

 activity .of preceding generations, a form of heredi- 

 tary skill. 



In the last decade, however, the general conception 

 of instinct has undergone an essential transformation 

 through August Weismann's neo-Darwinism. I can 

 not here, of course, go thoroughly into the highly com- 

 plex grounds of this theory of heredity.^ Weismann 

 postulates an hereditary substance carried on continu- 

 ously through succeeding generations, the germ plasm 

 (Keimplasma # ) which is present in the so-called chro- 

 mosomes, or colourless bodies of different shapes inside 

 the cell nuclei ("chromatin bodies" or "chromatin 

 nuclei "). He not only asserts in a general way that this 

 substance inside the germ cells must have an exceedingly 



* Der menschliche Wille, p. 62. 

 f Ibid., p. 32. 



% See especially Die ContinuitSt des Keimplasmas, Jena, 1885. 

 Amphimixis oder die Vermischung der Individuen, Jena, 1891. 

 Das Keimplasma, Jena, 1892. 



* Keimplasma, p. 32. 



