n 



EXTEKNAL DIGESTIVE SECEETIONS 



125 



XVI. To study pure succus entericus (which is the product of 

 all the secretory cells of the small intestine, both in the external 

 epithelium of the villi, and in the epithelium which lines the 

 crypts of Lieberkiihn internally) it is necessary to isolate a loop 

 of intestine, closing one end by stitches while the other is sutured 

 to the wall of the bowel, after bringing together the two ends 

 of cut intestine, so as to re-establish the continuity of the gut 

 (Thiry's method). It is more convenient to stitch both ends of 

 the intestinal loop, separately, to the abdominal walls, so as to 



PIG. 44. Section of mucous membrane through commencement of duodenum at pylorus. (Klein.) 

 v, villi ; 6, apex of a lymphoid nodule ; c, crypts of Lieberkiihn ; TO, muscularis mucosae ; s, 

 Brunner's glands cut more or less obliquely ; d, ducts of pyloric glands of stomach ; g, 

 oblique section of same ; t, deeper tubes in submucous tissue, corresponding with Brunner's 

 glands of intestine. 



make two fistulous apertures communicating with each other by 

 the loop (Vella's method). 



During inanition, according to Boldireff (1905), the secretion 

 from Vella's loop is scanty, with a rhythmical maximum and 

 minimum cycle of about 2 hours 5-6 c.c. of succus entericus can 

 be collected altogether in 8 to 10 hours. 



Some authors say that mechanical stimuli (sounds, sponges, 

 etc.) introduced into the loop are able to excite a true secretion 

 there, even during hunger. But according to U. Lombroso, 

 these stimuli only excite a small increase in the flow of secretion, 

 which is probably due to increased peristalsis. 



Electrical stimuli are more effective than mechanical. The 

 effects of chemical stimuli are better known (Frouin, Lombroso, 



