I9II] Alfred P. Lothrop 91 



zymophorous groups in the enzyme molecule. Rennin Solution 

 filtered through a Berkefeld filter loses its milk-curdling power to 

 a greater extent than its power to neutralize anti-rennin. The Solu- 

 tion seems to contain enzyme molecules with both groups, and 

 molecules with the haptophore group alone. The pores of the 

 filter apparently retain a larger proportion of the former than of 

 the latter. 



Enzymes closely resemble toxins in that they stimulate the tis- 

 sues to form anti-bodies; anti-rennin, anti-pepsin, and trypsin, etc. 

 It seems probable that every enzyme injected under proper con- 

 ditions would induce the formation of a specific anti-body. This 

 is an argument in support of the protein-like nature of the enzymes, 

 although there is also evidence against this view. 



Investigations on invertase and diastase indicate that enzymes 

 are made up of two parts, a combination of a colloid (a mannose- 

 gum in the case of invertase) with an active principle (protein in 

 nature). The colloid is generally related chemically to the sub- 

 stance upon which the enzyme acts; for example, mannose-gum 

 in invertase and arabanose gum in diastase. So long as the enzyme 

 is combined with its carrier it remains inactive but is broken away 

 by slight changes in reaction. In the cells the various enzymes may 

 thus be anchored and rendered inert in combination with colloids. 

 They may accumulate in this inert form, from which slight local 

 changes in reaction set them free to produce their characteristic 

 action locally.^ 



Many or most of the chemical processes occurring in living 

 cells are dependent on the action of intracellular enzymes, directly 

 or indirectly, and naturally their great importance has attracted 

 very many workers to this field of research. As yet very little is 

 definitely known regarding their chemical structure and of the 

 way in which they are combined in the cell in spite of the vast 

 amount of work that has been done upon them. When these two 

 points have been definitely established a great many of the life 

 processes will be understood which are now extremely obscure. 



* Matthews and Glenn : Loc. cit. 



