168 FUNCTIONS OF NUTRITION. 



mixture. The pancreatic juice acts in this way like a solution of 

 albumen. Its emulsifying power is not due to its alkaline reaction, but 

 Ito the organic matter which it contains ; since its alkalescence may be 

 Neutralized, as shown by Bernard,* without sensibly impairing its 

 activity in this respect. The instantaneous effect thus produced on 

 the fats is limited to their emulsion. They are disseminated through 

 the fluid in the form of minute particles, but their chemical characters 

 are not Altered until other changes occur at a later time. 



Among the albunienoid ingredients of the pancreatic juice are 

 substances belonging to the class of ferments, which exert three 

 distinct actions on alimentary substances ; namely, a tran sforniing 

 action on starch, a digestive action on coagulated albumen, and a partial 

 acidifying action on fats. All these substances may be precipitated by 

 alcohol from pancreatic juice, or extracted by water or by glycerine 

 from the pancreatic tissue ; but they nave not been obtained in a state 

 of purity, or even distinctly separated from each other, to the satis- 

 faction of physiological chemists. 



The first of these substances, the so-called pancreatine, is a diastatic 

 ferment ; that is, it has the power, like vegetable diastase, of trans- 

 forming starch into glucose. It produces this change very readily at 

 the temperature of the body, and it may be preserved under alcohol or 

 in glycerine for an indefinite time without losing its properties. When 

 dry, it may be heated to 100 C., and still retain its catalytic power; 

 but in watery solution, it is coagulated and rendered inactive by a boil- 

 ing temperature. It is produced in the gland, probably by the trans- 

 formation of some previously formed substance, since it has been found 

 by Liversidge,f that after it has been completely extracted by glycerine 

 from the chopped glandular tissue, the inactive residue, if exposed to 

 the air for five or six hours, will regenerate the ferment, so that it may 

 again be extracted by water or glycerine. This ferment exists in the 

 pancreas and the pancreatic juice of every animal thus far examined. 

 The second ferment, known as trypsine, is that which causes the solu- 

 tion of albumenoid matters. This property of the pancreatic juice, first 

 observed by Bernard and Corvisart, has been the subject of many exper- 

 iments, among the most valuable of which are those of Ku'hne. j This 

 observer operated both with the pancreatic juice of the dog and with 

 infusions of the glandular tissue. He found that the fresh viscid 

 secretion could, in from half an hour to three hours, eifect the solution 

 of coagulated fibrine arid albumen, without modification of its alkaline 

 reaction. If the process be arrested at this point no putrefactive 

 changes take place in it ; but if continued for a longer time, it gives 

 rise to the products of decomposition. The activity of this ferment is 

 greatest in an alkaline solution ; it goes on, though with less energy, 



* Liquides de POrganisme. Paris, 1859, tome ii., p. 346. 



f Studies from the Physiological Laboratory of the University of Cambridge, 

 Part I. Cambridge, 1873, p. 49. 



% Archiv fur pathologische Anatomic und Physiologic, 1867, xxxix., p. 130. 



