26 PRINCIPLES OF PHYSIOLOGY 



placed under the microscope and a drop of 

 water be allowed to impinge on the edge of the 

 morsel, curious twisted or spiral structures 

 may be seen shooting out. These myelin 

 forms, as they are called, are instructive, as 

 showing lifelike movements in dead matter 

 depending on changes in surface tension. 

 Some have even asserted that living matter is 

 essentially a kind of froth, and that the 

 structural forms are similar to those seen 

 when one blows a mass of soap bubbles 

 Walls and partitions may then appear, 

 and even one part may seem to be within 

 another, not unlike certain structures seen 

 in a thin section of living matter. Such 

 imitation- 'forms, however, do not imply life. 

 11. Evolutional History. A living being, 

 during the course of its existence, passes 

 through phases that follow each other in a 

 certain order. It originates in a germ which is 

 developed in a parent, that is, in a previously 

 existing being that has essentially the same 

 structure and properties. This germ, which 

 is known as the spore, seed, or egg of plants 

 and animals, is a cell, a comparatively simple 



