THE LIVING SUBSTANCE. 133 



[126] Thus much seems certain, that the power of the sub- 

 stance to transport itself by contraction from place to place, 

 either within or without the mass, either as organism or as sub- 

 stance, either as a whole or as portions too minute for us to 

 trace; its power by the same property to subdivide, or consoli- 

 date, the alveolar inclusions of all the foam structures we can 

 detect, and to transport them also hither and thither within its 

 mass; and especially the power shown by the substance in its 

 utmost simplicity or complexity of organization known to us, 

 to select its own specific environmental conditions i; these 

 things underlie at some point or other of their progress, all the 

 manifold and complex phenomena seen in the animal world. 



All the phenomena of ^gg development seen in the Metazoa 

 as all the phenomena of areal formation in the Protozoa, how- 

 ever fleeting, may be expressed in terms of these results as due 

 to organizing activities of the continuous element, tendino- 

 always to more radical and sensitive selection of its environ- 

 mental conditions as a basis for organized activities. 



The segregation of yolk and pigment matter to certain areas 

 during larval development, which is so finely shown in rotifer, 

 starfish and echinus eggs as well as in many others; the con- 

 verse segregation from many eggs with huge yolk masses, of 

 the living substance, thus setting it free for its organizing 

 development, are typical instances of such substance choice of 

 physiological environment. The pursuit of light, heat, oxygen, 

 or of other conditions among the opportunities of external 

 environment show action of the organism as a procuring device 

 for the substance as such. The formation of contractile and 

 irritable structures in response to stimulus, as described in a 

 previous section, yields a still larger and more strongly typical, 

 though closely allied, group of phenomena. Though due 

 always to one final cause as stated above, protoplasmic organ- 

 ization and reorganization has two aspects and is brought about 

 in two ways. In one of these, greatest prominence seems to 

 be given a placing of inclusions with respect to the substance, 



1 It is not claimed here that the substance can do this apart from its normal 

 conditions or state of being, therefore experiments upon excised or mutilated por- 

 tions of cells or areas have no bearing on the question. 



