18 



LIVING AND LIFELESS MATTER 



muscular, others sensory, supporting, reproductive, etc., the 

 form of the organism being due largely to the supporting cells 

 and products. With the exception of the amorphous types all 

 animals, even the unicellular ones, have fairly definite axes of 

 symmetry. Some, the globular ones, are homaxonic or similar 

 in structure in all planes passing through the center; others are 

 monaxonic, having but one axis of symmetry, with the mouth at, 

 or near, one extremity termed anterior, and the tail with vent 

 at the opposite end termed posterior. In such forms the mouth 

 side is ventral, the opposite or aboral side is dorsal. Still other 

 types are polyaxonic and, like Hydra, may be divided by in- 

 numerable vertical planes into symmetrical halves. 



FIG. 7. Lifeless matter in living cells, c, Groups of crystals of calcium oxal- 

 ate; i.e., intercellular space; , nucleus; s, starch granules; /, fat drops. (From 

 Sedgwick and Wilson.) 



The form of an animal or plant, dependent largely upon the 

 presence and activity of the supporting cells, is very often due 

 to the presence of lifeless matter within or around those cells 

 and created by them. In the majority of cases the form is 

 retained for a longer or shorter time after the living protoplasm 

 has died, hence form alone would be insufficient evidence of 

 living matter. Many lifeless things, such as crystals and lifeless 

 products of vital activity may also have definite forms, hence 

 neither this factor alone nor together with appearance would 

 give a complete manifestation of vitality. Living and lifeless 



