ANNUAL REPORT, 1936 93 



The tunica dartos muscle first showed marked reaction to temperature changes at 63 to 

 84 days in the ram and 105 days in the boar, while results with the bull were variable. With 

 boars, a low plane of nutrition resulted in a considerable retardation of the development 

 of the testes and also of the tunica dartos muscle. 



The evidence presented seems to indicate that the tunica dartos muscle is dependent 

 upon a testicular hormone for the development and maintenance of its sensitivity to tem- 

 perature changes. 



332 The Cranberry Industry in Massachusetts. C. D. Stevens, H. J. Franklin, 

 C. I. Gunness, and V. C. Peterson. 36 pp. illus. June 1936. 



As cranberries are a perishable product with a rather brief marketing season, it is im- 

 portant that those who grow and market them should have reliable estimates of the size 

 of the crop if it is to be sold to the best advantage. Such estimates are essential to the 

 development of sound advertising and price policies. To provide an adequate basis for 

 estimating the crop, special surveys of acreage, management, and production, and of 

 disposal of the fruit must be made from time to time, for it has been found that census 

 data and assessors' reports do not furnish adequate information. The present survey, 

 made in 1934, is compared with the last previous survey (1924), important changes in the 

 industry being noted. The statistical material is presented rather tully in tabular form, 

 and is freely illustrated with charts. 



333 A Study in Soil Nitrogen. F. W. Morse. 20 pp. July 1936. 



For twelve years, continuous production of nonleguminous crops has been compared 

 with the alternation of a legume with a nonlegume crop, and continuous absence of nitrogen 

 fertilizers, with the alternation of applied nitrogen with residual nitrogen. Analyses of the 

 soils showed no evidence of accumulation of nitrogen resulting from the application of nitro- 

 gen fertilizers or from the growth of legume crops; nor any depletion of soil nitrogen re- 

 sulting from continuous production of nonleguminous crops. On plots which had received 

 no nitrogen fertilizers for forty years, and where no legumes had been grown, the soil 

 appeared capable of supplying to nonlegume crops growing during the summer months an 

 average of 40 pounds per acre of nitrogen, with no measurable depletion. Grasses and 

 spring grains seemed unable to secure as large an amount of nitrogen from the soil without 

 nitrogen fertilizers. 



Results obtained with the legume crops are in accord with the accepted facts about the 

 synthesis of nitrogen from the air by symbiotic bacteria in the soil. Results with the non- 

 legume crops are strongly indicative of the presence in the soil of nonsymbiotic micro- 

 organisms which are adding to the supply of nitrogen that is available for such crops. 



334 Dried Blood as a Source of Protein for Dairy Cows. J. G. Archibald. 

 7 pp. October 1936. 



Dried blood has been compared, as regards its suitability for dairy cows, with a mixture 

 of soybean meal and cottonseed meal. From the standpoint of palatability and theabsence of 

 any unfavorable effects on the animals, itseems evident that dried blood can be safelyused as 

 a component of grain mixtures fed to dairy cows to the extent of at least 10 percent of the 

 mixture. In view of our general knowledge of the protein requirements of milking cows 

 and the fact that there was not a significant difference in milk production on the two rations 

 it seems reasonable to conclude that the blood was a satisfactory source of protein as a 

 substitute for a mixture of soybean meal and cottonseed meal. 



335 Some Factors Affecting the Properties of Whipping Cream and the Quality 

 of the Finished Product. W. S. Mueller, M. J. Mack, and H. G. Lind- 

 quist. 24 pp. illus. November 1936. 



A mechanical whipper of constant speed was used in all these studies, and other conditions 

 were carefully controlled so that accurate comparisons are possible. Some of the factors 

 studied were found to have little or no effect on whipping ability and quality of the whipped 

 cream — time and method of standardization using either whole or skim milk; aging for 

 more than 24 hours; variation in pasteurization temperature from 145 to 165° F.; homo- 

 genization; delayed cooling after pasteurization; increase in serum solids to 11 percent by 

 the use of skim milk powder or plain condensed skim milk; the source of protein in the feed 

 of the animals (vegetable or animal). Several substances designed to reduce serum drainage 

 were added to cream before pasteurization. Since they were of somewhat doubtful value, 

 and since the addition of any substance to whipping cream is illegal in many places, their 

 use cannot be recommended. 



A whipping temperature of 40° produced a better whipped cream than any higher tem- 

 perature; and a separation temperature of 90° proved better than 100°. Time of adding 

 sugar was important; but the addition of 5, 10, or 15 percent of sugar after 1 minute of 

 whipping had no detrimental effect. Reconstituted cream (butter and skim milk homo- 

 genized) was less desirable in whipping ability and flavor than fresh cream. 



