DEVELOPMENT OF CELL HABITS 245 



or ferments, converting one after the other molecular groups of 

 a particular order into antitoxin molecules. These are matters 

 not yet determined. It fits in better with our knowledge to 

 suppose that the toxin molecules determine a modification or 

 rearrangement of certain side-chain molecules, which in their 

 turn lead to the building up of other side chains of like con- 

 stitution. But, whatever the exact process, here is an exquisite 

 example of a cell habit of the automatic type. Once started 

 in their new work of producing antibodies, the cells continue 

 to produce them, and this without external stimuli, developing 

 them from the usual food-stuffs assimilated by the cell. 



It follows, thus, that we may recognize two orders of cell 

 habit of the automatic type : first, as afforded in my original 

 instance, the exaltation of a property already possessed by the 

 cells ; and, second, as exemplified by this last instance, the 

 acquirement by the cell under abnormal environment of new 

 properties — an acquired cell variation becoming, if I may so express 

 it, converted into a cell heredity. 



Underlying both we must see a manifestation of that most 

 potent cause of metabolism, namely, enzyme action. In other 

 words, it is the existence of intracellular enzymes that permits 

 both continuous and cyclic automatic cell activities. If the 

 view be accepted which I have put forward elsewhere, namely, 

 that organic enzymes are of the nature of detached side chains 

 of the proteidogenous molecules — able, on the one hand, to 

 attach themselves to the main ring ; on the other, to molecules 

 of food-stuffs, bringing about their dissociation, with eventual 

 building up of like side-chain material in series, — then we can 

 realize how, so long as side-chain molecules of a particular order 

 are present in the cell, and that cell possesses its usual nutrition, 

 the enzyme action will continue within that cell until arrested 

 by the concentration of the products of that action ; to become 

 active again so soon as those products become used up, diffused 

 out, or otherwise removed. Once enzymes appear or become 

 developed within a cell, we have the conditions most favourable 

 for continuous cell activity, irrespective of alteration in environ- 

 ment or external stimulus, save that afforded by the exhibition 

 and regular absorption of food-stuffs. And when abnormal 

 bodies of proteid type — toxins — gain entrance into the cell, I 

 would lay down that they have affinity to side chains of the 



