246 mr. s. le m:. moore's studies 



III. Sections kept in Water for three weeks. 

 Fig (M), (X), (E). As in fresh sections. 

 Arundo Fhragmites. Ditto. Ditto. 

 Maize (M), (X), (E). Reaction as with fresh tissues 

 Rosa canina (M), (X), (11). Quite normal. 

 Ash (M), (X), (E). Normal in every way. 



Krasser's List of Bodies reacting like Proteids not an 



exhaustive one. 



TJpon the general question we now stand in this position. 

 The substance giving these proteid reactions cannot be protein 

 unless 



(a) it be some unpeptonizable proteid, or 



(b) it be a proteid which has entered into some unpeptonizable 



combination with cell-wall substance. 

 That (b) should express the truth seems highly improbable. 

 "With regard to (a), although not impossible, one may remark 

 upon its a priori unlikelihood, and the question may be asked, 

 What is proteid doing in the wall ? Surely, to use up so complex 

 a body over such a task as forming the actual substance of the 

 wall must argue what seems to us great improvidence on the part 

 of the plant, supposing other means to be available. Moreover, 

 it is highly significant, from an objector's point of view, that 

 proteid reactions are given best by the walls of lignified ele- 

 ments — elements useful for support and for conduction of fluid, 

 but at the same time elements in which metabolism either soon 

 ceases or but feebly persists. So far, however, Wiesner's theory 

 seems to be preferable to Fischer's, because, while unpep- 

 tonizable proteids are known to exist, we do not know of in- 

 soluble compounds with tyrosin. A solution of the problem 

 might possibly be found could we discover some substance 

 which, while giving proteid reactions, will free us from the 

 necessity of supposing that we are dealing with a body which, 

 when it reaches the cell- wall, suddenly becomes transformed 

 from what it was, so that if a proteid it is now unpeptonizable, 

 if tyrosin it becomes insoluble in acids and alkalies. More- 

 over, if our supposed substance belongs to a class of bodies known 

 already to exist in the cell-wall; if its presence there can be micro- 

 chemically proved by a series of tests other than those employed in 

 the detection of proteids ; still further, if the same series of 



