374 EXPERIMENT STATION RECORD. 



The relation of ptyalin concentration to tlie diet and to the rate of secre- 

 tion of the saliva, A. J. Carlson and A. L. Crittenden (Amer. Jour. Physiol., 

 26 (1910), No. 1, pp. 169-177, fig. i).— Experimental data obtained with both 

 man and animals are reported and discusserl. 



Quotations from the authors' summary follow : 



'• Ju man weak acetic acid in the mouth ajipears uniformly a more efficieut 

 stiumlus to secretion by the parotid than mechanical stimuli, such as dry saud, 

 crackers, flour, or cotton. . . . Withiii limits the stronger the acid tbe greater 

 the i*ate of secretion. This difference between efficiency of mechanical and 

 acid stimuli is probably only one of intensity of stimulus. . . . 



" We have made a number of determinations of the relation of concentration 

 of the human parotid saliva to the rate of the secretion of the saliva, and find 

 that it is the same as in the lower mammals, namely, within limits the concen- 

 tration of the saliva increases with the rate of the secretion. . . . 



'* In man, in the case of individuals who respond readily with varying 

 secretion rates to stimuli of varying strengths, the saliva that is secreted the 

 fastest exhibits the greatest digestive power. . . . 



" Qualitatively different stimuli in the mouth, such as acid, salt, sweet, 

 bitter, mechanical, agreeable, disagreeable, yield .no constant difference in the 

 ptyalin concentration of the parotid .saliva, unless they yield a constant and 

 marked difference in the rate of secretion, as is the case, for example, with 

 sand and acids. In man it is practically inii)ossible, however, to secure uniform 

 secretion x'ates in the case of the qualitatively different stimuli. Our results 

 are therefore not conclusive on this point. But it is obvious that any investi- 

 gation of the relation of ptyalin concentration or of tbe concentration of other 

 substances in the saliva to different stimuli in the mouth or to different 

 physiological states of the reflex centers must recognize the secretion rate 

 factor." 



The influence of heat on the tryptic digestion of egg albumen, J. Talarico 

 (Voiniti. R(iiil. ,s'oc. Biol. [I'aris]. US (1910), So. I.i, i>i). (KiJ-OG't). — The digesti- 

 bility of raw and cooked egg albumen by trypsin was studied, the results being 

 expressed on the basis of the amount of amido acid tV'i'med in a given time. 



When raw egg white was compared with egg white cooked for varying times 

 the cooked material was found to be more digestible than the raw. The digesti- 

 bility increased at first with the length of time the cooking was continued and 

 then again decreased, the maximum being observed when the cooking was con- 

 tinued for 50 minutes. When the cooking period was 10 hours the digestibility 

 was about the same as for 10 minutes. 



As regards the digestibility of egg white raw and egg white cooked for 15 

 minutes at different temperatures, the amount of amido acid products was the 

 same for raw egg white and for that cooked at 60° and at 70° C. Above this 

 temperature an increase in digestibility was noted, the maximum amount being 

 found at a temperature of 140°, the highest experimental temperature recorded. 



The effect of excluding pancreatic juice from the intestine, J. H. Pratt, 

 P. D. Lamson, and H. K. Marks (Trans. Assoc. Amcr. Physicians, 2Jf (1909), 

 pp. 266-281). — From an experimental study of the question, in which dogs wei'e 

 used as subjects, the following general deductions were drawn : 



" In every instance in which the pancreatic secretion was excluded from the 

 intestine there was marked diminution in the absorption of nitrogen and fat. 

 The lack of absorption was not due to the absence of a fat-splitting enzym, for 

 the proportion of split fat in the feces was normal. The disturbance in metabo- 

 lism did not develop gradually, but was noted as soon as the animal recovered 

 from the oiJeration. It persisted as long as the animals were under observation, 

 which in one case was 5 mouths and in another 4 months. The animals lost 



