72 CONSTITUTION OF LIVING MATTER 



same generic substance, whether existmg as the 'contents' of 

 animal and vegetable cells, or as naked masses of protoplasm— 

 whether as parts of higher organisms, or as single independent 

 living units. The recognition that all these various forms are but 

 trifling alterations of a single great genus of primitive organisable 

 material, and that in all cases this ''albuminous material is the 

 original active substratum of all vital phenomena, may," says Prof. 

 Haeckel, "perhaps be considered one of the greatest achievements 

 of modern biology, and one of the lichest in results." 



Protoplasm then, in its most general and undifferentiated con- 

 dition, in the form of a naked contractile mass, of seemingly 

 homogeneous, semi-fluid jelly, is the variable substratum for all the 

 life-movements of the lowest living things, even in their adult 

 condition. A minute structureless mass of jelly, now in one now in 

 another isomeric state, suffices for the display of all the vital 

 phenomena of the lowest organisms. Here, without the aid of 

 organs of any kind, are carried on the vital phenomena of ' growth ' 

 and 'reproduction' ; here do we see the first germs of that organic 

 irritability and contractility which attain their highest development 

 in the conscious sensibility and power of movement possessed by 

 those living things that stand at the head rather than at the foot 

 of organic nature. 



