70 MASS. EXPERIMENT STATION BULLETIN 388 



in this study. The yeast fermentation method was used to measure the urinary 

 excretions of thiamin and pyrimidine for each individual on graded levels of 

 thiamin intake. There appears to be a sex difference in the excretion of thiamin 

 which is not apparent in the excretion of pyrimidine. The response of people 

 in this age group to increased thiamin intake is similar to that of younger people 

 as far as excretion is concerned. Two out of eight subjects reported no subjective 

 reaction to increased thiamin intake, two noted definite improvement in chronic 

 constipation, four felt less fatigued or "peppier," two enjoyed improved appe- 

 tites, and one noted an increased thirst. 



Cause and Control of Nutritional Cataract. (H. S. Mitchell, G. M. Cook, and 

 A. W. Wertz.) The experimental production of cataract in rats by feeding rations 

 containing galactose has become a means of studying the effect of various dietary 

 factors upon the lens. Since it has been well established by earlier work in this 

 laboratory that a deficiency of protein aggravates cataract development and that 

 a liberal supply delays it, the question naturally arose as to what factor in protein 

 is responsible for the protective action. Anti-cataractogenic action of certain 

 nitrogenous factors is being studied. 



1. The Influence of Certain Diamino and Dicarhoxylic Amino Acids upon 

 the Cataracto genie Action of Galactose. (H. S. Mitchell and G. M. Cook.) Follow- 

 ing the lead suggested by work reviewed in the 1940 Annual Report, certain 

 individual amino acids are being investigated. It was reported that the enzymic 

 hydrolysate of deaminized casein was somewhat more protective than the deam- 

 inized casein from which it was prepared. Of the fractions, the diamino-di- 

 carboxylic acid fraction of the enzymic hydrolysate afforded as much protection 

 as the whole hydrolysate, while the monoamino and proline and peptide fractions 

 showed no protection. Since glutamic acid, histidine, arginine, and lysine are 

 present in the protein hydrolysate fraction found to be most protective, these 

 amino acids have been incorporated in a low-protein galactose ration in order 

 to study any protective action. One of these amino acids has indicated slight pro- 

 tection. It and related compounds are being studied further. 



2. Time Factors in the Development of Galactose Cataract. (G. M. Cook and 

 H. S. Mitchell.) It has been observed in this and other laboratories that young 

 rats are more susceptible to galactose injury than older rats. An experiment de- 

 signed to investigate the question of this age factor is in progress. Rats from the 

 same litter are started on experimental rations at fortnightly intervals. The one 

 started later required a longer time for lenticular injuries to become evident. The 

 complete data are not yet available. 



The injury due to galactose seems to persist in rats after they have been trans- 

 ferred to rations containing none of this sugar. The blood sugar returns to normal 

 within a few hours after the ratioij^ 'change is made. The apparent lag in the 

 galactose injury must be due to slow diffusion from eye fluids. The extent of this 

 lag is being investigated b}' discontinuing the galactose ration at four-day 

 intervals in a series of rats from the same litter. 



The Nutritive Value of the Iron of Cocoa and Iron-Fortified Cocoa Mixtures. 



(F. Kinder and H. S. Mitchell, with the cooperation of W. S. Mueller of Dairy 

 Industry.) Inasmuch as iron is precipitated in the presence of tannic acid and 

 from 2 to 15 percent of tannic acid is present in commercial cocoa, there arises 

 the question of the availability of the iron in cocoa and foods associated with it. 

 The current use of chocolate milk and chocolate-flavored foods makes the prob- 

 lem one of practical interest. 



The nutritive value of the iron of cocoa and iron-fortified cocoa was determined 

 by biological procedure. The iron of cocoa was not so well utilized (approx- 



