CHEMICAL DYNAMICS OF ANIMAL NUTRITION 135 



The intestine was cut out from below the pylorus to just above 

 the iko-coeoal valve. It was opened up longitudinally and nailed down 

 on a wooden board. The surface of the mucous membrane was care- 

 fully cleansed with cotton wool, and the mucous membrance was scraped 

 off with the blunt edge of a knife. Scrapings were made alternately 

 from the cardiac and the coecal end, and put into a tube and thoroughly 

 mixed with a knife. The tube was stoppered until it was required for 

 weighing out. The weighings were all made as soon as possible after 

 killing the animals. 



For the determination of total nitrogen the tissue was mixed with 

 sulphuric acid in a Kjehldahl flask immediately after weighing. The 

 portions of tissue required for estimation of the nitrogen of the 

 coagulable albumen were mixed with sulphate of soda immediately after 

 weighing. This mixture could be kept till wanted. 



The animals used were always cats, except when otherwise stated. 

 They were fully anaesthetized by A.C.E. mixture, and bled to death by 

 opening the carotid artery when under the influence of the anaesthetic. 



The blood was collected in a tall cylinder and allowed to clot. 

 The serum was then poured off into a narrower cylinder, and the 

 corpuscles, which were decanted off with the serum, allowed to settle. 

 The required quantities of serum were pipetted directly, either into 

 the Kjehdahl flask or into the flat-bottomed dish, according to whether 

 the total N or the N of the coagulum was to be estimated. 



Various morphological details were noted, such as weight, weight 

 of liver, length of intestine, etc. In order to know the concentration 

 of residual nitrogenous bodies, the total solids were estimated. In the 

 case of serum this was done by heating about 2 c.c. in porcelain crucibles, 

 first at about 60 and afterwards in a Victor Meyer bath jacketed with 

 toluol at 107 C. The mucous membrane and liver were treated in 

 the same way ; instead of using a crucible, however, they were dried 

 after spreading out as much as possible on a watch glass. In this case 

 the ordinary paired watch glasses were used. Heating was continued 

 to constant weight. The fed animals were killed about five hours after 

 the last meal. 'I he fasting animals were killed when the stomach was 

 empty. The animals were killed in pairs, a fed and fasting animal 



