527 



The couclusious from the experiments were as follows : 



(1) Common salt alone dissolves the albuminoids of cotton-seed meal 

 to a very small extent only. Cottonseed meal was therefore a favora- 

 ble material for the investigation. 



(2) The amount of nitrogen dissolved by 0.05 per cent hydrochloric 

 acid is greatly increased by the addition of NaCl. Thus, the addition 

 of O.L'o per cent NaCl to the 0.05 per cent HCl solution increased the 

 relative amount dissolved from 7 to 41. With 0.1 per cent HCl the 

 increase from the addition of minute quantities of NaCl was small, and 

 with the addition of 1 ])er cent NaCl the solvent action was diminished. 

 With 0.2 per cent HCl, small quantities of NaCl increased the action 

 of the acid (increase from 53 to 71, with 0.25 per cent NaCl), but 1 per 

 cent NaCl diminished the action of the acid. In other words, in HCl 

 (without pei)sin) the larger the amount of salt added the smaller was the 

 increase in the amount of nitrogen dissolved, and when nu)re than 1 per 

 cent NaCl was added the amount dissolved was less than by 0.1 per 

 cent HCl solution alone. 



(3) With pepsin the case is very diiferent. More albuminoids were 

 dissolved by acid pepsin with 1 percent of NaCl than by that contain- 

 ing 0.25 or 0.5 per cent NaCl. 



(4) NaCl increases the solvent action of the acid pepsin solution, 

 more albuminoids having been dissolved in every case with than with- 

 out it. The action was the most favorable when in addition to the salt 

 0.05 or 0.1 per cent HCl was present, and the most unfavorable when 

 0.2 per cent HCl was present. The author believes that these exj)eri- 

 nients indicate anew the high value of common salt in digestion, espe- 

 cially where the acid content of the mucous membrane of the stomach 

 is below the normal. 



Chdtujes in the digestibility of albuminoids caused by the heating of foods 

 and feeding stuffs. — It was formerly believed that the steaming of feed- 

 ing stuffs increased the digestibility of the protein. It has been proved 

 in digestion experiments on animals that this is not the case,* and that 

 with wheat bran the higher the temperature and the longer the steaming 

 is continued, the more indigestible the albuminoid materials become. 



The author's object was to determine whether this change in the 

 digestibility of protein could be detected by means of experiments with 

 artificial digestion outside of the animal, and in particular whether the 

 method of ai)proxiinatIng the value of albuminoids recently [)roposed 

 byhimist sufticiently sensitive to show such tine differences in the 

 digestibility. In experiments made some 8 years ago, but not published, 

 the author found that when egg albumen, i>alm cake, cocoa bean, and 



*Laiul\v. Jabrbiicber, 1879, p. 933; Laudw. Versucbs-Stationen, 29, pp.214. 



t Landw. Versucbs-Stationen, 37, p. 132. The details are givoii of a metbod by 

 wbicb tbo amount of uitro<^on dissolved from 100 iiiilligrains of nitrogen in form of 

 pepsin-soluble albuminoids by 0.05, 0.1, and 0.2 per cent HCl, botli witli and witbout 

 pepsin, is determined. 



