Sect. V, 1922 [27] Trans. R.S.C. 



III. The Preparation of Pancreatic Extracts containing Insulin 



By F. G. Banting, M.C, M.B., C. H. Best, M.A., J. B. Collip, 

 Ph.D., and J. J. R. Macleod, M.B., F.R.S.C. 



(Read May Meeting, 1922) 



1. The Preparation of the Earlier Extracts (F. G. Banting and C. H. 



Best) 



In two previous papers a brief outline of the preparation of 

 pancreatic extracts has been given. Active anti-diabetic extracts 

 of degenerated gland, exhausted gland, foetal gland, and finally adult 

 beef gland, were made. The main problem in the preparation was 

 to get rid of or avoid the presence of proteolytic enzymes. 



The first extract used was obtained by ligating the pancreatic 

 ducts of the dog, and waiting from seven to ten weeks for degeneration 

 of the acinar tissue. The remnant, which contained healthy insular 

 tissue, was removed and macerated in ice-cold Ringer solution. By 

 this procedure a non-toxic extract which markedly reduced the blood 

 sugar and the excretion of sugar in diabetic dogs was obtained in 

 small quantity. Active extract was also prepared from the pancreas 

 of a dog that had been injected with secretin. 



The foetal calf extract was at first made by macerating pancreas 

 of foetal calves of under four months development in Ringer's 

 solution and filtering. Later, 95 per cent, alcohol was used in place of 

 Ringer's solution. 



The alcoholic filtrate was evaporated to dryness in a warm air 

 current and the resin-like residue redissolved in saline. This solution 

 when injected subcutaneously or intravenously into a diabetic dog 

 caused a marked fall in blood sugar and in sugar excreted in the urine. 

 It was further found that this extract did not contain trypsin, that 

 it was destroyed by boiling, that the active principal was insoluble 

 in 95 per cent, alcohol and that daily injections enabled a totally 

 depancreatized dog to live a much longer time (70 days) than has 

 hitherto been recorded after such an operation. 



Potent extracts of the whole gland of the adult ox were obtained 

 in a similar manner, using equal volumes of 95 per cent, alcohol and 

 pancreas, with the exception that the alcohol was made 0.2 per cent, 

 acid by the addition of HCl. It was found that the fatty substances 

 in the extract could be removed by washing twice with toluol without 



