362 BOTANICAL GAZETTE [November 



Terminology 



* 



Biological terms of uncertain connotation will be considered 

 when the term is first used. I shall discuss briefly a few important 

 words in colloid chemical nomenclature which have no fixed and 

 precise meaning to either chemist or biologist, although they are 

 extensively used by both. Thomas (26) has recently published 

 an account of the nomenclature employed in colloid chemistry, 

 and has in most instances suggested the preferable term to use. I 

 shall follow his terminology strictly, with the possible exception 

 of the words "gel," "jelly," and "coagulum," regarding which 



Thomas comes to no definite decision. 



In view of the widespread and lax use of the term gel it seems 

 advisable to use the word for the general condition of a colloidal 

 sol when it hardens, whether the hardening be through pectization, 



gulation 



RAHAM 



setting (of a gelatine sol, 



example), that is, gel includes both the stiffened jelly-like 



form 



will 



tiffening 



Bechhold 



gulation as coagula. 2 Thus do we also have the corresponding 



form gels; set, to 



form coaeula 



asm 



t of three terms where two might suffice may 

 some respects, but it has much to recommend 

 is the colloid being studied. When protoplasm 



1m 



mass is a coagulum or a jelly. If the hardening is excessive an 

 undoubted coagulum results, for the living substance is then 

 irreversible, and can be cut up into solid chunks, while, if the 



2 Thomas (26, p. 12) states that Bechhold restricts "gel" to the coagula of sols, 

 and terms stiffened sols "jellies." The former statement is not supported by 

 Bechhold's more recent work (3, p. 4) where he says: "It seems preferable to me 

 to use the expression "gel" for the general comprehensive phenomenon, and to re- 

 serve the word "jelly" for the gelatinization of a hydrophile colloid" (that is, for 

 the gelatinized hydrophile colloid). 



'12) employs the last two terms in the same way. "The production 



Hardy 



stiffening 



>j 





