77//; N7M77-; OF Till: srcM! i\ Tin: r.i.ooh 643 



a rule hiiilicr tliaii iiDniial. l)iit not iicct'ssafily so, iiiucli (l('])eM(liii<z; on 

 the watci' halaiu't'. .loslin's statistics show a raii^e of 0.07 to 0.4:> 

 per cent. 



THE STATE OF THE SUGAR IN THE BLOOD 



It has k)n<>- been believed that tlie sii<iar circiUatin<;' in the Ijlood 

 exists ill two physical states, a diffusible and a non-difrnsiblc, i.e., as 

 (a) Free ghicose in a state comparable to that of glucose dissolved in 

 water, sucre actueUe of Lcpine. (b) Sugar in a colloid state, Sucre 

 rirtuelle, Lepine. By the former term a very specific idea is conveyed. 

 One might think for instance of single molecules or clusters of two or 

 three, each holding in its sj^here of intluence a certain number of 

 water molecules like suns in solar systems. Such small masses move at 

 high velocities, "diffuse" readily and create high "osmotic pres 

 sures. " By the latter term is meant sugar in the blood which does 

 not behave physically like glucose in aqueous solution nor respond to 

 the ordinary chemical tests for sugar, but from which free glucose may 

 be reliberated by such simple procedures as boiling with dilute acids. 

 Such sugar is supposed to exist as a component of particles having the 

 larger dimensions which characterize colloids (non-diffusoids). But 

 as to the actual chemical nature of these a great variety of proposals 

 have been made. Thus Pavy proposed glucose molecules held entire 

 to the colloids of the blood in a state of simple adsorption (comparable 

 to the state of molecules of a dye electrically bound to particles of a 

 colloid clearing agent). He also proposed glucose chemically incor- 

 porated in the structure of the protein molecule, and between these 

 extremes by the same author a score of suppositions have been made 

 by others, among which Drechsel's jecorin, a lecithin-sugar compound, 

 is a notable example. Another worthy of serious consideration is 

 that of glucose built up into polymers intermediate between disac- 

 charides and glycogen. The basis for assuming the existence of com- 

 bined sugar in the blood lies chiefly in the observation that following 

 glucose administrations the increase in the reducing power of the 

 blood which results from heating the blood with dilute acid is greater 

 than the increase resulting from the same process before sugar admin- 

 istration (see Pavy, Lepine, Loewi). Also, if glucose is added to fresh 

 blood and the mixture placed in the incubator, the reducing 

 power falls but may be in part rehabilitated by boiling with dilute 

 acid.^" 



As to the sugar wliidi is determined by the ordiiuiry methods 

 of blood analysis, it would ai^jieai- that we are dealing almost ex- 

 clusively with free glucose. As yet no one has succeeded in prov- 



10 A critical review of the literature to 1012 will he found in the hooks hy 

 IMcLeod and Allen. Compare also the article hv Levene and the recent studies 

 of Lombroso favoring the polymerization idea. 



