ANNUAL REPORT, 1937 39 



Absorption by Food Plants of Chemical Elements of Importance in Human 

 Physiology and Nutrition. (E. B. Holland, W. S. Ritchie, and W. S. Eisenmenger.) 

 Work on this project was confined to an association with the investigators at the 

 Waltham Field Station. Tomatoes and lettuce were grown in the greenhouses 

 rather than in the open and were fertilized with compounds of iron, manganese, 

 copper, and iodine. In the case of the tomatoes both the vines and the fruits 

 were saved. Growing the vegetables under glass has the advantage that the 

 samples are cleaner and freer from soil than when grown in the open. Since the 

 analyses are dealing with minute quantities of the elements, freedom from soil 

 particles is important. The samples thus obtained were added to that group 

 being analyzed in the previous project. 



The Carbohydrates in Kentucky Bluegrass. (Emmett Bennett.) The pro- 

 cedure and outstanding results of previous years have been given in the Annual 

 Reports of 1935-36. Data obtained in 1937 indicate that the content of structural 

 carbohydrates increases with maturity and that these values are greater in the 

 morning than at night; that the content of sucrose decreases with maturity but is 

 greater at night than in the morning. Results of this investigation will soon be 

 ready for publication. 



Hemicelluloses of Tobacco Stalks. (Emmett Bennett.) A polyuronide hemi- 

 cellulose from the cured stripped stalks of Havana seed tobacco has been isolated 

 and studied. Upon hydrolysis the polyuronide yields xylose as the chief sugar. 

 Details of this study have been published in Industrial and Engineering Chemistry 

 {Industrial Edition) 29: 933, 1937. 



Bacteriostatic Effect of Lignin. (Emmett Bennett.) Because of the bacterio- 

 static effect isolated lignin has been known to exert on decomposing plant material, 

 it was believed that the intestinal flora of the rat might be changed by the inges- 

 tion of a diet high in lignin. Thus far results obtained in feeding a small number 

 of rats do not indicate a definite change in the intestinal flora. Limited data, 

 however, indicate that the ingestion of a high lignin diet by the rat is accompanied 

 by losses in carbohydrate and nitrogen fractions. The lignin ingested may be 

 recovered almost within limits of experimental error. The experiment is to be 

 repeated with a larger group of animals during the coming year. 



The Vitamin A Content of Pasture Grasses. (W. S. Ritchie and J. G. Archi- 

 bald. Cooperative with Animal Husbandry.) In 1936 the vitamin A content 

 was determined in samples of sheep fescue, Rhode Island bent, bluegrass, red 

 top and timothy. The work of 1937 continued the assays for the vitamin A con- 

 tent of these grasses from both fertilized and unfertilized plots. Duplicate samples 

 were available from these plots during the early growing season (June) and during 

 the later period of growth (August). Samples of orchard grass and sweet vernal 

 were added to the five reported on in 1936. 



The data indicate that, generally speaking, the vitamin A content is higher 

 in the grasses from the fertilized plots than from the unfertilized. The seasonal 

 variation does not seem to be as great as that attributed to the application of 

 commercial fertilizers. 



Chemical Changes in the Cooking of Vegetables. (Monroe E. Freeman and 

 W. S. Ritchie.) Chemical factors contributing to texture rating of cooked pota- 

 toes were investigated in two mealy and two waxy varieties. (These terms are 

 used here according to definitions outlined in Maine Agricultural Experiment 

 Station Bulletin 383, p. 344.) The four samples were obtained, in part, on the 

 open market and came from different localities. The same varieties have since 



