ANIMAL, PRODUCTION. 767 



" The action of potassium salts never appeared to be poisonous, for a complete 

 recovery of a muscle and nerve was obtained after perfusion of all concentra- 

 tions of tbe salt. . . . 



" Tbe action of lactic acid corresponded closely with that due to tbe excessive 

 fatigue of an overworked muscle. Tbe nerve endings were very markedly 

 affected, and their subsequent recovery from tbe effects of the acid took some 

 time. The effects produced are almost entirely due to tbe hydrogen ion. 



" Under tbe conditions assumed to exist in a bard working muscle, even such 

 traces of lactic acid as have been found in ' resting ' muscle were found capable 

 of abolishing tbe indirect response for some time. Hence it was considered that 

 lactic acid must be neutralized, and that tbe limit of tbe working capacity of the 

 intact muscle is reached at tbe stage when lactic acid has been produced so as 

 to be present in the free condition beyond the merest traces. When such free 

 lactic acid is present, tbe subsequent recovery of tbe indirect response will show 

 a more or less marked delay, e. g., stiffness. 



"A possible role of creatin is tbe neutralization of lactic acid ; and where 

 this is insufficient, ammonium lactate, with subsequent formation of purins, 

 may represent a further attempt at such neutralization. 



" The hydrogen ion is a necessary concomitant of waves of variation in the 

 response of a fatigued muscle." 



Contribution to the physiology of the intestine, U. Lombeoso (Arch. Far- 

 maool. Sper. e. Sci. Aff., (1910), Nos. 6, pp. 262-288; 7, pp. 289-298).— A series 

 of experiments which have to do with the functions of the intestinal tract is 

 reported and discussed. 



The bacillus of long' life, L. M. Douglas (London wnd Edinburgh, 1911, pp. 

 YII-\-16-'i, pis. 57, figs. 5). — Tbe author has collected and summarized a large 

 amount of historical and other data with reference to tbe theory that the use in 

 the diet of soured milks of different sorts tends to prevent putrefactive changes 

 in the intestine and so favors health and longevity. Such subjects are con- 

 sidered as tbe bacteriology of fermented or soured milk, tbe preparation of 

 soured milk in the house and in the dairy, and soured milk in health and dis- 

 ease. The book, as a whole, is a collection of data which might be considered as 

 favoring the theory advanced rather than of evidence on tbe question as a 

 whole. 



ANIMAL PRODUCTION. 



Nutritive value of cholla fruit, A. E. Vinson and W. H. Ross (Arizona 

 Sta. Rpt. 1910, pp. 396, 397). — From the digestive coefficients found for cholla 

 fruit (Opuntia fulgida) and from other investigations it is estimated that not 

 less than 45 lbs. of cholla fruit would be required daily for a sheep of 120 lbs. 

 shorn live weight. This would contain over 1.3 lbs. of mineral matter, of which 

 0.5 lb. would be absorbed and require elimination by tbe kidneys. On one- 

 fourth of this amount of cholla fruit, supplemented by a little alfalfa, the 

 feces would no longer remain normal, and any marked increase would lead to 

 scouring. 



A nitrogen metabolism experiment with cholla fruit, supplemented by alfalfa 

 and water-grass hay, showed that a sheep receiving 2 oz. of alfalfa daily and 

 cholla fruit would not be able to maintain indefinitely its nitrogen equilibrium. 

 When about i lb. of alfalfa and a like amount of water-grass hay was given 

 with cholla fruit ad libitum, of which about 4 lbs. was eaten, the nitrogen 

 balance was restored. 



From these results it is estimated that from ^ to i lb. of alfalfa and 6 or 

 more pounds of cholla fruit would maintain a sheep indefinitely in a lean but 



