104 



PANCREAS. 



The exact nature of Frerichs' ivater extract 

 Schmidt's organic matter is not deter- 

 mined ; it is a substance resembling albumen or 

 casein, but not identical with albuminate of 

 soda, with casein, or with ptyalin. It coagu- 

 lates only imperfectly when heated (probably 

 from its containing an alkali), is precipitated 

 by acetic acid, but slowly redissolved in an 

 excess, especially if heated ; it is precipitated 

 by nitric acid and by alcohol; on the addition 

 of chlorine-water it separates in grayish flakes. 

 It is to this substance that the pancreatic fluid 

 owes its principal chemical and physiological 

 properties. 



Bernard found a considerable quantity, and 

 Frerichs a smaller amount ('020 per cent ) of 

 a butter-like fat. 



The pancreatic secretion is peculiarly prone 

 to putrefactive change. Bernard found that 

 when exposed to a low temperature, it might be 

 kept for many days, and that by the reduction 

 of the temperature the viscidity was increased, 

 approaching a jelly-like firmness. If, on the 

 other hand, it was kept at a temperature of 

 40 to 45 centigrade (about 105 Fahr.), it 

 became rapidly modified, and in the lapse of a 

 few hours quite altered, giving out a nauseous 

 odour, presenting a cloudy deposit, and losing 

 its property of coagulation by heat. In the 

 heat of summer and in stormy weather, this 

 change takes place almost instantaneously, so 

 that great care is necessary in maintaining at 

 a low temperature both the pancreatic fluid 

 and the animal furnishing it, lest the alteration 

 should take place whilst it is still in the vessel 

 in which it is being collected. Frerichs found 

 that after exposure to the air for a few hours 

 it developed a distinct odour of putrefaction. 

 Bernard observed that the deposit that was 

 produced at the moment of the alteration of 

 the fluid, had sometimes a peculiar soft, silky 

 appearance, and he always round in that case, 

 on examining it by the microscope, a large 

 quantity of acicular crystals, having the cha- 

 racters of crystals of margarine or margaric 

 acid. 



The secretion is not constant, but intermit- 

 tent, and is entirely regulated by the process 

 and stages of digestion ; all observers agree in 

 this. Bernard killed three dogs in three dif- 

 ferent conditions with regard to the function 

 of digestion one just after a meal, as diges- 

 tion was just commencing ; another four hours 

 after a meal, when digestion was at its height ; 

 and a third after a twenty-four hours' fast. 

 In the first, the tissue of the pancreas was 

 slightly turgid with blood, and the secretion 

 the most abundant, and this lie has always 

 found to be the case ; he collected upwards of 

 two grammes an hour ; in the second, the 

 pancreas was highly turgid " goujfc de sang, 

 et commc erectile," and the amount secreted 

 less than a gramme an hour ; in the third it 

 was white, exsanguine, the duct empty and 

 collapsed, and the amount secreted in many 

 hours hardly enough to moisten the inside of 

 the little reservoir adapted for its reception. 



The information respecting the absolute 

 quantitative relations of the secretion is very 



defective. We have seen that Leiiret and 

 Lassaigne obtained three ounces from the 

 horse in half an hour, and Bernard from the 

 dog thirty-one grains an hour; Frerichs col- 

 lected three hundred and eighty grains from 

 an ass in three quarters of an hour, and forty- 

 five from a hound in twenty ^five minutes ; but 

 these statements, as well as those of Colin*, 

 become valueless from the fact that the ani- 

 mals experimented on were not weighed. The 

 most reliable estimate is that of Bidder and 

 Schmidt ; they say a dog yields a grain and a 

 half per hour for every two Ibs. of weight ; 

 therefore an adult man weighing about 140 Ibs., 

 would secrete in twenty-four hours nearly five 

 ounces of pancreatic juice, containing 225 

 grains of solid residue. But it is doubtful 

 whether any safe data as to quantity are fur- 

 nished, or can be furnished, by any expcri- 

 fnents made by measuring the amount pro- 

 cured artificially from the living animal ; the 

 abnormal condition of the gland produced by 

 the experiment must be such, and the conse- 

 quent disturbance of the secretion so great, as 

 to throw doubt on the most careful and exact 

 estimates. The case in which the quantity 

 seems most likely to be normal is that in which 

 the secretion is obtained, as in some of Ber- 

 nard's experiments, from a permanent fistulous 

 opening. All observers confirm Bernard's 

 statement as to the exsanguine and passive 

 condition of the gland in animals fasting. 



The natural stimulus of the secretion is, 

 no doubt, the digestive process going on in 

 neighbouring organs, producing, through the 

 medium of the sympathetic nervous connec- 

 tions, a vascular engorgement of the pancreas 

 and an exalted nutrition of its secreting 

 agents. Possibly the pressure from a dis- 

 tended stomach may have something to do 

 with it ; and there is reason to think that the 

 presence of food in the duodenum is both a 

 stimulus to the secretion and to its discharge ; 

 for on the application of chemical and me- 

 chanical stimuli to the inner surface of the 

 duodenum near the orifice of the duct, the 

 amount discharged is sensibly increased. 

 Possibly food of one nature in the duodenum 

 may be a more exciting stimulus to the se- 

 cretion than another. Whether this is so, 

 whether the amount secreted would be ex- 

 cited more by an animal than a vegetable 

 food, whether it bears the same relation to 

 the volume of the gland in Carnivora and 

 Herbivora, or whether the volume of the 

 gland is always a direct measure of the amount 

 secreted, are questions upon which, as yet, 

 our information is very defective. They are, 

 however, not unimportant questions ; for 

 there is every reason to believe that the 

 quantity secreted is always in proportion to 

 the exigencies of the digestive process, and 

 their solution might therefore throw some 

 light upon the function of the secretion. 

 There can be no doubt that muscular move- 

 ment and pressure facilitate the discharge of 

 the fluid, as most observers, from De (5raaf 



' Comptes Rcudus, vol. xxxi. p. 374 , ami 

 vol. xxxii. p. 85. 



