4 THE WORK OF THE DIGESTIVE GLANDS. 



With each advance in technique \ve reach a higher level from which a 

 wider field of vision is open to us, and in which we sec events previously 

 out of range. 



Our first problem consisted, therefore, in the working out of a 

 method. We had to observe how the reagents were discharged upon 

 the food brought into our digestive factory. To accomplish this in an 

 ideal manner required the fulfilment of many and difficult conditions. 

 Thus it was necessary to be able to obtain the reagents at all times, 

 otherwise important facts might escape us. They must be collected in 

 absolutely pure condition, if we were to determine how their composi- 

 tions varied. We must be able to estimate their quantities accurately ; 

 and, lastly, it was necessary that the digestive canal should function 

 normally, and that the animal under experiment should be in perfect 

 health. 



It is but natural that the solution of these difficult problems 

 should only be gradually achieved by physiology, that not a little 

 trouble should be spent in vain, and that many investigators should 

 see their efforts fruitless, notwithstanding that several of the most 

 prominent representatives of our science have devoted their attention 

 to this field. 



We begin our consideration with the pancreas, as the simpler case. 

 It might appear that here our problem was very light. We have appa- 

 rently only to seek out the duct through which the secretion of the 

 gland is delivered into the intestine, to fasten a cannula into it, and 

 thereby afford a free outflow of the fluid towards the exterior, collecting 

 it in a graduated cylinder. All this, in reality, is very easily done, but 

 our problem is far from being solved ; for digestion may be very active, 

 yet, as a rule, there is no flow of pancreatic juice from the tube after 

 the operation ; or if there is one the quantity is very small and obviously 

 sub-normal. In such a case it would be out of the question to observe 

 the rate of secretion, still more to determine the alterations in the juice 

 dependent upon the nature of the food. On following the matter 

 up, it became evident that the gland is a very sensitive organ, and 

 suffers such a severe disturbance of its activity from the unavoidable con- 

 ditions of the operation (narcotisation, opening of the abdominal cavity), 

 that in the majority of instances not even a trace of normal function 

 remained. This method is known in the literature under the name of 

 " temporary " pancreatic fistula ; its want of success naturally led to 

 attempts being made on other lines. 



It was hoped that an improvement might be attained by collecting 

 the juice some time after the completion of the operation, that is, when 

 its disturbing influence had fully passed away. The fluid was therefore 

 allowed to escape freely from the excretory ducts for a considerable time. 



