THE WONDERS OF LIFE 



unicellular body, broad, flaplike processes of the naked 

 cell body which constantly change their form, size, and 

 place. If they are killed and examined with the aid of 

 the best methods of coloring, it is quite impossible to 

 detect any structure in them ; and this is also true of the 

 pseudopodia of the mycetozoa and many other rhizopods. 

 Moreover, the slow flowing movement of the fluid proto- 

 plasm shows clearly that there cannot be any composi- 

 tion out of fine fixed elements in the body. This is 

 particularly clear in those amoebae and mycetozoa in 

 which a hyaline, firm, and non-granulated skin-layer 

 (hyaloplasm) is more or less separated from a dark, 

 softer, and granulated marrow-layer (polioplasm) ; as 

 both of them are viscous and pass into each other 

 without sharp limits, there cannot be any constant and 

 fixed structural features in them. 



Organic life — in its lowest and simplest form — is 

 nothing but a form of metabolism, and therefore a 

 purely chemical process. The whole vital activity of the 

 chromacea, the simplest and oldest organisms that we 

 know, is confined to that process of metabolism which 

 we call plasmodomism or carbon-assimilation. The 

 homogeneous and structureless globules of protoplasm, 

 which represent the whole frame of these primitive pro- 

 tophyta (chroococcus, aphanocapsa, etc.) in the simplest 

 conceivable way, expend their whole vital power in the 

 process of self -maintenance. They maintain their indi- 

 viduality by a simple metabolism; they grow by the 

 addition of fresh plasm obtained by it, and they split up 

 into two equal globules of plasm when the growth passes 

 a certain limit — reproduction by clevage, maintenance of 

 the species. Thus these chromacea have neither special 

 organs, or organella, that we can distinguish in their 

 simple plasma-bodies, nor different functions in their 

 life-process; it is wholly taken up with the primitive 

 work of their vegetal metabolism. We shall see later 



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