168 THE NATURE AND ORIGIN OF LIFE 



Apart from this special case, through all changes of the 

 medium, however considerable, provided they do not dimin- 

 ish the being's vitality, its form changes so little that we can 

 always easily recognize it. But when the conditions are 

 such that the being continues to live, we know that by assimi- 

 lation pure and simple or by functional assimilation it 

 keeps very nearly its colloid and chemical properties. Here 

 we already have a glimpse of this remarkable result in con- 

 ditions of survival, where constructive phenomena triumph 

 over destructive, even a soft-bodied being preserves its 

 personal form with so little change that the eye can always 

 easily recognize it. 



On the other hand, we know that the form of a soft-bodied 

 being depends not only on its bodily structure, but also on 

 the mechanical conditions realized in its environment. A 

 drop of not-living viscous substance carried around in whirls 

 of running water takes the form of the whirlpools. On the 

 contrary, a drop of living substance, so long as it continues 

 to live through considerable variations of mechanical con- 

 ditions, keeps its form with little modification although the 

 form certainly depends on the mechanical conditions which 

 are realized outside of it. The evident conclusion is that, 

 while it lives, a living substance by the act of living creates 

 in the environment around its semi-fluid body whirlpool 

 movements which count for a great deal in the determination of 

 its own form. Thus, just so long as it survives, the living 

 being carries along with it, not only its own substance, but 

 also a certain system of movements which it imposes on the 

 medium in the immediate environment of its body. This is 

 important enough to be verified experimentally. 



First of all, we can easily understand the origin of these 

 whirlpool movements. The living mass, plunged in the 

 watery medium, occupies a limited volume in this medium. 



