42 



E, S. EDIE 



very rapidly after birth. Rakoczy [1910, 1911] and Van Hasselt [1910] found 

 that in the case of calves the rennin disappeared rapidly during the first 

 month after birth, while the pepsin increased greatly. The youngest animal 

 employed by Rakoczy was apparently nine days old, but Van Hasselt does 

 not state the exact age of the animals he used. In my experiments the stomachs 

 of rabbits were taken as soon as possible after birth, washed out thoroughly 

 and ground up with twice their weight of water. A little chloroform was added 

 and after three days the liquid was filtered ofE and the filtrate tested. The 

 stomachs of adult rabbits were tested in exactly the same way. The extracts 

 were subjected to no further treatment with acid, sodium chloride or other 

 substances such as were used by Hammarsten and others with a view to 

 destroying the proteolytic or milk coagulating action as the case might be. 



In the coagulating experiments 1 cc. of extract together with 5 cc. of milk 

 was kept in a water-bath at 37° and examined every five minutes. Coagulation 

 was considered complete when the test tube could be inverted without dis- 

 turbance of the contents. Experiments were always repeated three times at 

 least. 



The proteolytic experiments were carried out on fibrin which had been 

 finely minced, thoroughly washed and heated to 85°. 1 cc. extract + 40 cc. 

 iV/20 HCl + 1 g. fibrin were kept at 37° for a certain time and then filtered, 

 the nitrogen being determined in the filtrate by Kjeldahl's method. Controls 

 (HCl + fibrin) were also done and allowance was made for the amount of 

 nitrogen originally present in the extracts. 



The results are expressed as the number of cc. of decinormal nitrogen 

 obtained from the fibrin digested. 



Results of experiments: 



A. New-born rabbits (each represents a different litter) : 



Coagulation 

 time 



12 minutes 



18 



30 



12 



13 



22 „ 



B. Adult rabbits : 



Coagulation 

 time 



No coagulation in 2 hours 



1 hour 



2 hours 

 2 „ 



These results show the very wide differences which exist between the 

 gastric extracts prepared from young and adult rabbits respectively with 

 regard to their content of rennin and pepsin. 



(508) 



