THE LIVING SUBSTANCE. 109 



optically by subdivisions of a visible structure, but which the 

 known subdivisions of this again extend, and which the phe- 

 nomena of the invisible substance prove to have no limit assign- 

 able by us. A concrete instance will help to an understanding 

 of this broad statement. 



When an amceba, responsive to the touch of a passing organ- 

 ism, engulfs it, the protoplasm, obedient to its physical form, 

 surrounds as a pellicle the ingested mass, and thus that first 

 slight point of external touch becomes at once extended into 

 an internal contact many hundred, or thousand, times its first 

 area. As digestion proceeds, the chemically altered food be- 

 comes more or less a watery solution and in this form is grad- 

 ually diffused throughout the whole organism until, both by 

 this and by wandering of interalveolar material and of vesicles 

 of Butschli's structure, the living substance may to its farthest 

 morsel suffer change of environment, which may be by way 

 of extension, or renovation, or actual change, of stimuli at 

 multiple contact surfaces formed by lamellar films. 



Thus by ingestion of food is the specific environment of the 

 substance not only extended but perennially renewed. Nor do 

 the phenomena differ in any essential in those higher organisms 

 furnished with most stable and complex machinery for the dis- 

 tribution as well as ingestion of food. These facts hint that 

 there is a more extended significance than has been understood 

 in the habit of reducing food substances to a diffusible form, 

 for they are now seen to be thus prepared not for the stomach 

 membrane only, but for the universal physical form of the 

 living substance. 



The subdivisibility of the foam structure, the general physi- 

 cal plasticity of such a form, plays an important role in arrange- 

 ment, and in procuration also, of specific, internal environments 

 for the living contact surfaces or vesicular films. For, as was 

 shown above, relatively large quantities of inclusion substances, 

 as well as of living substance, can be transported through, or 

 amongst, very stably organized areas of physiological function 

 to other parts of the mass, or even outside it. 



From the physical form of the substance results great 

 economy too of the vital stuff. Growth of areas, masses, or 



