FOODS HUMAN NUTRITION. 867 



"A high acidity value does not neeess;irily mean that the flour is made from 

 imsound wheat. It means that it contains a large proportion of those streams 

 which should go into a lower commercial grade or that the method of milling 

 in regard to cleaning or purification is faulty." 



Experiments and observations on bread, with special reference to the 

 causation and prevention of dental caries, J. S. Wallace (Proa. Roy. Soc. 

 Med. [London], Odontol. Sect., 4 {1911), No. 8, pp. 90-1 0-i) .—From this experi- 

 mental study the author concludes in general that " the cause of dental caries 

 is the undue lodgment of fermentable but nondetergent carbohydrates in more 

 or less immediate contact with the teeth, and undisturbed by the free access 

 of saliva." 



With reference to bread, he believes that "no farinaceous foodstuff in gen- 

 eral use in this country is less harmful to the teeth than bread when eaten with 

 butter, and no farinaceous foodstuff is more beneficial from the point of view 

 of oral hygiene; especially is this the case when the bread is eaten wtih a goodly 

 proportion of crust. 



"The difl'erent varieties of bread (i. e., white, standard, and stone-milled) 

 make no appreciable difference in inducing dental caries, beyond the difference 

 which the physical differences of the bread make in their detergent effects on 

 the teeth. That is to say, the less finely ground may be presumed at least to 

 have the more detergent effect." 



As regards the detergent effect, " the crust is always preferable to the crumb 

 in all varieties of bread. Similarly, toasted bread of any variety is preferable 

 to untoasted bread of any variety." 



The paper is followed by a discussion. 



Action of dissolved substances upon the autofermentation of yeast, A. 

 Harden and S. G. Paine (Proc. Roy. Hoc. [London], Ser. B, S// (1912), No. B 

 574, pp. 4Jf8-.'t59, dgms. 2). — The production of carbon dioxid by autofermenta- 

 tion. of yeast is brought about, the authors point out, by the action of at least 

 2 enzyms. " The reserve material of the cell, for the most part glycogen, is 

 first converted by a glycogenase into a sugar, which in turn is fermented by 

 zymase with the production of alcohol and carbon dioxid. As the rate of auto- 

 fermentation is considerably less than that produced by the same yeast in 

 presence of excess of sugar, it follows that the rate of autofermentation is con- 

 trolled by the rate of production of sugar within the cell, in other words, by 

 the rate of action of the glycogenase. An increase in the rate of autofermen- 

 tation, therefore, indicates greater activity in this enzym within the cell." 



The effect of solutions of various sorts on the autofermentation of yeast was 

 studied. 



Some of the conclusions follow : 



"All dissolved substances which plasmolyze the yeast cell also cause a large 

 increase in the rate of autofermentation. . . . 



" The effect produced by salts is probably a direct result of the concentration 

 of the cell contents due to plasmolysis. but in the case of toluene it is possible 

 that some other factor (such as disorganizatioji of the cell, or hormone action) 

 is concerned." 



Spices, prepared mustard, honey, and gluten flour, C. D. Woods {Maine 

 Sta. Off. Insp. S'l, pp. 109-121/) . — The results of the examination of a number of 

 samples are reported. 



The chemical action of organic acids of canned goods upon tin, A. BARrLL^ 

 {Jour. Phann. et Chim.. 7. ser., J, {1911), No. 9, pp. 39C,, 397; ahf<. in Zentbl, 

 Biocltem. u. Biophyi^., 12 {1912), No. 15-16, p. tO.'i).— Data regarding the action 

 on canned goods of such organic acids as sarcolactic acid and of acid salts 

 are presented. 



