54 MASS. EXPERIMENT STATION BULLETIN 441 



was constructed. It contained all the known ingredients necessary for good 

 growth. The observation that some of the rats fed this ration had cavities on 

 the grinding surfaces of their teeth came as a distinct surprise. As a result of 

 these findings many rats have been reared on diets containing raw or cooked 

 corn starch as their sole source of carbohydrate. Caries has been found in all 

 groups fed such rations. Experiments are now in progress to determine the 

 conditions under which tooth decay will result in the presence of starch. It is 

 felt that research on diets containing raw or cooked starches provides a promising 

 line of investigation since few human beings consume diets in which the major 

 portion of their carbohydrate is sugar. 



Tooth Decay Studies: Raw Corn Contains a Caries-Inducing Factor. (Julia 

 O. Holmes, L. R. Parkinson, Anne Wertz, and Lois Brow.) A "corn-meal" diet 

 is used in most laboratories today to produce tooth decay in experimental ani- 

 mals. This diet is composed of 66 parts of coarsely ground whole corn, 30 of 

 whole-milk powder, 3 of dried alfalfa meal, and 1 of pure table salt. Since this 

 diet is notorious for the rampant caries it produces, it was decided to feed various 

 fractions of corn to determine whether or not a fraction could be found which 

 had cariogenic properties. The corn fractions were obtained from the Corn 

 Products Refining Company, Argo, Illinois. They included a crude corn oil 

 obtained from the corn germ: corn steepwater, which contained the major part 

 of the water-soluble minerals and vitamins of the kernel; zein, one of the corn 

 proteins; and a gluten fraction which contained, in addition to the corn gluten, 

 zein and some of the corn xanthophyls, and which assayed about 50 percent pro- 

 tein. To the basal ration into which these fractions were incorporated, corn 

 starch and 15 percent casein were added as the sole carbohydrate and protein. 

 The rations were ground to the fineness of flour. The rats receiving corn steep- 

 water developed no more tooth decay than did their brothers and sisters receiving 

 the basal diet only. In contrast those receiving gluten, zein, and crude corn oil 

 had twice as many sites of decay as did their controls on the basal diet. This is 

 the first demonstration of the presence, in a food, of an agent which accelerates 

 the decay of teeth. The findings suggest that, if sugar is a cariogenic agent, 

 it may be only one of many. One of the plans for the immediate future is to de- 

 termine the nature of the cariogenic factor in corn. 



DEPARTMENT OF HORTICULTURE 

 R. A. Van Meter in Charge 



Control of Weeds in the Nursery by Chemical Sprays. (C. H. Gilgut, Wal- 

 tham.) Of the chemical weed killers in common use at present, the industrial 

 solvent Savasol No. 5 shows most promise for control of weeds in the nursery. 

 It was extensively tested in 1946 in the Field Station nursery and in nearby com- 

 mercial nurseries. As a result, a number of the more progressive nurseries are 

 using this weedicide in their weed control program. The oil is used undiluted. 



So far, the best method of applying the oil is with a hand operated tank spra3'er 

 equipped with a nozzle that gives a flat fan-shaped spray. This gives good con- 

 trol of the spray and permits wetting weeds close to a plant without wetting the 

 plant enough to injure it. 



