ANIMAL PRODUCTION. 375 



weislit. Those that were free from postoperalive coiiipHcations bad a ravenous 

 appetite. The operation did not produce fjlycosuria. Additional evidence that 

 the loss of fat and nitrogen in the feces was caused by lack of the external 

 pancreatic secretion is shown by the increase in absorption when pancreatic 

 ferments were siven by the mouth. The failure of other investigators to obtain 

 a diminished absorption of fat and nitrogen after ligating the pancreatic ducts 

 was evidently due to the fact that pancreatic juice continued to enter the 

 intestine." 



The paper is followed by a discussion. 



The amount of ammonia, phosphoric acid, acid bodies, and amino acids in 

 urine, L. de Jager {Zcnthl. Gcsam. Physiol, u. Path. Stofftax'hsels, n. ser., 5 

 (I'JIO), No. 7, pp. 241-255, dgms. 6). — Data are summarized and experiments 

 reported. 



As regards the effect of diet on urine, it was noted that when the mid-day 

 meals consisted chiefly of fish or pancakes there was an increase in acidity, 

 and that the acid content was very low when foods containing much alkaline 

 salts were eaten — ^for instance, potatoes and green vegetables. Such effects, it 

 is i)ointed out, are often more noticeable on the following days than on the 

 experimental day. 



ANIMAL PRODUCTION. 



Explanatory remarks concerning the normal rate of growth of an indi- 

 vidual and its biochemical significance, T. B. RonioRTsoN (Biol. CenthL, 30 

 (I'JlO), No. 9, pp. oH)-S2f)). — The author discusses the objections raised by 

 Pearl (E. S. R., 21, p. 469), Enriques, and others, concerning the theoretical 

 curves for expressing the normal rate of growth. 



"This objection of Pearl's would be a perfectly valid one provided (1) that 

 there were no systematic errors in the experimental determinations, (2) that 

 there were no distui'bing factors such as deposition of fat, senile decay, etc., 

 and (3) that the constants of the theoretical curve were computed from the 

 experimental determinations by the method of least squares," conditions not 

 fulfilled in the present case. An additional explanation is given as follows: 

 "The experiments of Peter and of Loeb upon the temperature coefficient of 

 growth have shown that the velocity of growth is determined by the velocity 

 of chemical reactions. Now the growth of an organism, as the results of a 

 very large number of investigators have shown, undergoes, in the first part of 

 a growth cycle, positive acceleration and, later, negative acceleration with 

 time. . . . Only two groups of chemical i-eactions are known which display 

 positive acceleration — the one group consists of the autoeatalysed reactions 

 and the other of certain catenary reactions. But the curve expressing the 

 extent of transformation with time, in a catenary reaction, is almost invariably 

 markedly asymmetric about its iwint of inflexion, whereas that expressing the 

 extent of transformation with time in an autocatalytic reaction is symmetrical 

 about its point of inflection. Simple inspection of the numerous published 

 curves of growth is sufficient to assure us that the curve of growth, in any 

 given growth circle, is almost invariably notably symmetrical about its point 

 of inflection' We can not, I think, avoid the conclusion, from these con- 

 siderations alone, that the growth of living tissues and organisms is the ex- 

 ]»ression of an autoeatalysed chemical reaction." 



Growth and its analytical representation, P. Enriques {Biol. CcntbL, 29 

 (WOO), No. II, pp. 331-352). — Other formulas besides those of Robertson (see 

 above) are suggested as applicable to represent the growth of organisms. 



