266 EXPERIMENT STATION EECOED. [Vol.36 



of pancreas, undergoes esterification, and from control experiments it seems 

 most likely that this is a real action by the pancreas." 



Analysis of the intestinal mucosa during starvation and after feeding 

 showed that an esterification of a large part of the absorbed cholesterol had 

 taken place. No evidence was found that the mesenteric lymph nodes took 

 any part in cholesterol absorption. 



The cholesterol esters were found to be more resistant to the ordinary active 

 bipases, no evidence of splitting being found, although neutral fat in the same 

 mixture was easily saponified. In the opinion of the author the data obtained 

 by no means explain the whole process of cholesterol absorption. 



" Since no effect of the mucosa could be demonstrated in vitro, it is at 

 least possible that the esterification may take place in the lumen of the in- 

 testine under the influence of the pancreatic juice, and that the esters may 

 be absorbed as rapidly as formed." 



A study of the electrolytic method of silver cleaning, H. L. Lang and C. F. 

 Walton, Jr. (U. S. Dept. Agr. Bui. U9 (1916), pp. i2).— This bulletin reports 

 the results of a laboratory investigation of the so-called electrolytic method of 

 cleaning silver by bringing it in contact with a more active metal, like 

 aluminum or zinc, while immersed in a solution of some electrolyte. Pre- 

 liminary tests were made with a number of commercial devices, which 

 showed that these are generally satisfactory. A number of factors influencing 

 the efficiency of the method were studied, such as the effect of temperature 

 and concentration of the cleaning solution and the relative advantages of zinc 

 and aluminum as the active metal and of sodium carbonate and sodium bi- 

 carbonate as the electrolyte. Also, directions were formulated for the house- 

 hold application of this method. 



Aluminum was found to be more satisfactory than zinc as the active metal, 

 because the zinc soon becomes covered with a layer of basic zinc carbonate and 

 hence loses its efficiency. Sodium carbonate or sodium bicarbonate, with or 

 without the addition of sodium chlorid, was found to be equally effective as 

 the electrolyte. It was found that the cleaning solution should be kept at the 

 boiling temperature to secure the most satisfactory results. 



The loss in weight of sterling silver and plated silver spoons cleaned 50 

 times by the electrolytic method was from 1.9 to 4.3 mg. This was insig- 

 nificant and only about 4 per cent of the loss in cleaning with an abrasive silver 

 polish. This is due to the fact that in the electrolytic method the tarnish of 

 silver sulphid is reduced to metallic silver instead of being cut away by the 

 abrasive in the older type of silver polishes. 



ANIMAL PRODUCTION. 



The respiratory exchange of animals and man, A. Krogh {London and 

 New York: Longmans, Green & Co., 1916, pp. VIII+llS, pis. 3, figs. 31).— The 

 topics treated in this monograph are the physiological significance of the ex- 

 change of oxygen and carbon dioxid; methods for measuring the respiratory 

 exchange ; the exchange of nitrogen, hydrogen, methane, ammonia, and other 

 gases of minor importance; the standard metabolism or the organism (defi- 

 nism and determination) ; the influence of internal factors upon the standard 

 metabolism ; the influence of chemical factors upon the respiratory exchange ; 

 the influence of physical factors upon the respiratory exchange; the vari- 

 ations in standard metabolism during the life cycle of the individual ; and the 

 respiratory exchange in different animals. An extensive bibliography is in- 

 cluded. 



