228 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



lias been attributed, is in progress. Complete information on this 

 subject is necessary, in view of the recommendations now being made 

 by various dietitians that cottonseed meal be used as food for man. 

 The ojjtical crystallographic properties of gossypol have been de- 

 termined. 



The description of a transparent celluloid renal oncometer or plc- 

 thysmograph has been published. 



The services of the bureau's experts were furnislied the scientific 

 division of the Shipping Board and the Tariff Commission, in con- 

 nection Avith the consideration of drug and chemical products. 



PLANT CHEMISTRY. 



Seeds of about 40 individual plants of the mustards, Brassica 

 cciiiua and Brassica jiincca. grown in Illinois, have been examined 

 separately for essc'utial oil. In general, the volatile oil content of these 

 seeds Avas much above the average, reaching in some cases 1.5 per 

 cent. Seeds of the varieties from which the largest yields of oil 

 were obtained have been planted at Arlington, Va., for further 

 study. Under the title " Capsaicin, the Pungent Principle of Cap- 

 sicum,'' the results of the study of the constitution of the pungent 

 principle of red pepper have been published. It has been possible to 

 produce synthetically a series of substances of marked pungency. 



A report on the results of a survey on the caffeine content of tho 

 North American species of tlie genus Ilex, under the title " Ilex 

 vomiiona as a Native Source of Caffeine,'' is in press. Of the A'ari- 

 ous species examined, only Ilex vomltoria^ used since prehistoric 

 times by the Indians for the prej)aration of a beverage, was found 

 to contain caffeine. 



Department Bulletin 773, " Chemical Analyses of Logan Black- 

 berry (Loganberry) Juices," has been issued. 



To further the educational campaign to improve conditions in tho 

 production of tomato products, Avhich has been conducted for some 

 years, a paper on " Factory Investigations on the Manufacture of 

 Tomato Pulp and Paste " Avas printed in a trade journal. 



Articles upon the determination of the distribution of nitrogen in 

 certain seeds, upon the reduction of nitrates by seedlings, and upon 

 the effect of lime upon the alkali tolerance of Avheat seedlings have 

 been published. Studies of pumpkin and squash seed have been 

 completed. 



At the request of the Bureau of Plant Industry, the acidit}' of the 

 soil under certain special conditions Avas iuA^estigated. 



For the Bureau of Biological Survey manj^ samples of Avater from 

 North Dakota lakes Avere examined to obtain information regarding 

 the propagation of aquatic plants. 



In cooperation Avith the Bureau of Markets, an extensive surA'ey 

 is being made on the composition of cotton seed from various sections 

 of the country. In addition to the analyses made in the bureau, 

 00,000 analyses have been obtained from 27 other laboratories, and 

 arrangements to obtain from these laboratories similar analyses of 

 tiie 1918 crop have been comj)leted. Studies begun some years ago 

 to determine Avhether the oil content of a given sample of seed could 

 be estimated from the density of the seed, or the Aveight per thou- 

 sand, and the like, factors of Avorth in the evaluation of barley, 

 have not yielded results of value. 



