DIGESTIVE ENZYMES OF THE CHICKEN j|7 



and made up to volume after clearing with colloidal ferric hydroxide and 

 magnesium sulphate. The reducing sugar was estimated by the reduction of 

 10 cc. of Fehling's solution. The observed difference in reading indicated 

 whether hydrolysis had or had not occurred. No difference in reading was 

 observed in the case of the intestine or proventriculus, but a small though 

 distinct difference was always noticed in the case of the crop extract; it varied 

 from 0-2 to 0-5 cc. in a total of 10 or 10-1 cc. This slight difference indicated 

 an hydrolysis of 10-20 % of the lactose. 



(c) Lipase. This enzyme was not looked for except in the case of the 

 pancreas. Two exactly equal portions of oil in separate test tubes were made 

 just alkaline to phenolphthalein with 0-1 iV caustic soda. Enzyme and boiled 

 enzyme solution were added. On keeping at 37° and occasionally shaking, 

 the pink colour of the tube containing enzyme solution disappeared and it 

 was restored by adding a few drops of the soda. This could be repeated several 

 times and altogether from 1-2 cc. of alkali were added; the control tube did 

 not change colour. 



{d) Proteoclastic enzymes. Proteoclastic enzymes were detected by their 

 action on Congo-red fibrin in neutral, acid and alkaline media. In the first 

 case, a definite volume of enzyme solution and the same volume of boiled 

 enzyme solution were put into separate flasks; in the other cases the same 

 volumes of enzyme and boiled enzyme solutions were mixed with an equal 

 volume of 0-2 iV hydrochloric acid or 0-2 N sodium carbonate solution in 

 separate flasks; 1 g. of Congo-red fibrin and 2 cc. of toluene were added to 

 each and the several flasks were put in an incubator at 37° for one to seven 

 days. Solution of Congo-red fibrin, which, in the case of hydrolysis, generally 

 occurred in one or two days, was taken as indication of the presence of proteo- 

 clastic enzyme; solution did not occur in those flasks with boiled enzyme 

 solution. No investigation was made of the products of the hydrolytic action. 



Results. 



The presence or absence of enzymes in the various parts of the alimentary 

 canal is most easily seen from the following table: 



The distribution of the sucroclastic enzymes corresponds in most parti- 

 culars with that in the animal ; most animals have invertase in the intestine, 

 lactase is present in some, absent in others : diastase and lipase are generally 



