THE DIGESTIVE SECRETIONS 



949 



and to render the feces more slippery. In between the different villi, 

 however, the mucous membrane is pervaded by simple tubular glands 

 which are known as the crypts of Lieberkuhn. The latter are lined 

 throughout by a single row of columnar epithelium, among which are 

 found a few goblet cells. In the crypts of the large intestine, on the 

 other hand, these mucous cells increase in number and finally displace 

 the secretory cells altogether. This structural change is in complete 

 harmony with the fact that the crypts of the large intestine form only 

 mucus for purposes of lubrication. 



The Secretion of the Intestinal Juice or Succus Entericus. Un- 

 adulterated intestinal juice may be obtained by means of a fistula. 

 The method of Thiery (1864) consists 

 in isolating a loop of intestine by two 

 transverse cuts made at some distance 

 from one another. 1 The intervening 

 segment is left in connection with its 

 normal blood and nerve supply and 

 is brought close to the abdominal 

 wall. Its upper end is then closed 

 by sutures, while its lower end is 

 anchored to the sides of the wound 

 in the abdominal wall. The contin- 

 uity of the intestine from which this 

 loop has been obtained is restored 

 by an end-to-end anastomosis. Vella 

 advises to fasten both ends of the 

 isolated loop to the edges of the 

 wound in the abdominal wall. 



FIG. 502. DIAGRAM TO ILLUSTRATE 

 THE RELATION BETWEEN THE VILLI AND 

 THE CRYPTS OF LIEBERKUHN. 



V, Villus; G, goblet cells secreting 

 mucus; C, crypt of Lieberkuhn; L, 

 lacteal. 



The juice obtained from such isolated 

 segments of the small intestine is light yellow 

 in color, opalescent, very watery and strongly 

 alkaline in reaction. It possesses a specific 

 gravity of 1.010, and contains 1.07 per cent, 

 of solids, of which 0.2 per cent, are appor- 

 tioned to Na-jCOs and 0.58 per cent, to 

 NaCl. Its small content in proteins is made 



up of serum albumin and serum globulin. Its quantity is considerable, a short 

 segment of intestine furnishing as much as 200 c.c. of juice in the course of a 

 day. 2 One of the commonest means used to excite its flow is to introduce a rubber 

 tube through the fistnlous opening, but Pawlow states that the character of the 

 juice is then somewhat different from that obtained without this mechanical 

 stimulation, one of the points of difference being that it contains no enterokinase. 

 Its flow may also be increased by dividing the mesenteric plexus, 3 or by produc- 

 ing hydremic plethora. 



In the former case, a copious secretion sets in very shortly after the section of 

 these nerve fibers and continues for about 24 hours. Clear at first, the fluid soon 

 becomes cloudy and milky until it assumes the consistency of a thick broth. While 



1 Pawlow, Chirurgie des Verdauungskanals, Ergebn. der Physiol., i, 1902. 



2 Frouin, Compt. rend., Ivi, 1904, 461. 



3 Mendel, Pfluger's Archiv, Ixiii, 1896, 425. 



