260 THE AMEBIC AN NATURALIST [Vol.L 



The appearance of Ameba shows that the protoplasm is 

 made up of alveoli and inter-alveolar substances of differ- 

 ent density, representing colloidal and crystalloidal sub- 

 stances in a general mixture which Ostwald describes as 

 an emulsoid. Between these different substances con- 

 stant chemical activities are in progress, and the order- 

 liness which distinguishes these processes in the proto- 

 plasm of the living organism from similar processes which 

 go on in the same protoplasm when crushed, are possibly 

 due, as Mathews states, to the physical barriers of cellular 

 and nuclear membranes, alveoli, and the colloidal centers 

 of activity. The speed with which such processes take 

 place in living protoplasm, which, in itself, distinguishes 

 living processes from chemical processes in lifeless sub- 

 stances, is due to specific enzymes or catalyzers which 

 are manufactured as a result of chemical activities in living 

 protoplasm. These bring about and control each suc- 

 cessive step in the long chain of chemical actions involved 

 in destructive metabolism, the action in each event being 

 conditioned by the nature of the protoplasmic substratum. 

 In this chain of destructive processes different substances 

 may be formed which undergo no further oxidation or 

 other chemical change, but are stored up in the proto- 

 plasm until disposed of by excretion, these products, lead- 

 ing to changes in the protoplasmic substratum, i. e., to 

 protoplasmic chemical differentiation, may or may not be 

 accompanied by visible structural differentiations. Such 

 products of destructive metabolism, in the form, usually, 

 of nucleo-proteins or their derivatives, may act as poisons 

 to other organisms, as melanin does to the host in ma- 

 laria, or as the proteolytic ferments of Entameba his- 

 tolytica do in dysentery; or they may play some impor- 

 tant part in the vital activities of the organism itself, as 

 in phosphorescence of Noctiluca and the dinoflagellates, 

 or more generally, in regeneration and reproduction. 



Let me illustrate this latter point by some experiments 

 made on Uronychia transfuga, a ciliated protozoon. This 

 organism has rather a complicated structure with nine 



