GLANDS AND SECRETION OF THE INTESTINE. 465 



Various titration methods have been suggested for the estimation of the 

 free hydrochloric acid, but these cannot yield conclusive results for the reasons 

 given in a previous chapter (see estimation of the alkalinity of the blood-serum, 

 page 264). For this determination physico-chemical methods are necessary, 

 but they have not been used to any great extent for clinical purposes on account 

 of the difficulty in their manipulation. 



A great number of methods have been suggested for the quantitative estima- 

 tion of the total acidity, among which we must mention those of K. MORNER and 

 SJOQUIST, which are extensively used. As the value of a special determination 

 of the free and total hydrochloric acid is doubtful, or at least disputed, and also as 

 the question is chiefly of clinical interest we must refer to the hand-books of clinical 

 investigations of v. JAKSCH, EULENBURG, KOLLE and WEINTRAND and of SAHLI. 

 The same applies to the tests for volatiles fatty acids. 



HI. THE GLANDS OF THE MUCOUS MEMBRANE OF THE INTESTINE AND THEIR 



SECRETIONS. 



The Secretion of Brunner's Glands. These glands are partly con- 

 sidered as small pancreatic glands and partly as mucous or salivary 

 glands. Their importance is not the same in all animals. According 

 to GRUTZNER they are in dogs closely related to the pyloric glands and 

 contain pepsin. This also coincides with the observations of GLAESSNER 

 and of PONOMAREW, which differ from each other only in that PONOMAREW 

 finds that the secretion is inactive in alkaline reaction and contains only 

 pepsin, while GLAESSNER claims it is active in both acid and alkaline 

 reaction and that it contains pseudopepsin. According to ABDERHALDEN 

 and RONA the pure duodenal secretion of the dog contains a proteolytic 

 enzyme which does not belong to the trypsin type but rather. to the 

 pepsin variety. The statements as to the occurrence of a diastatic 

 enzyme in BRUNNER'S glands are disputed. SCHEUNERT and GRIMMER l 

 indeed found diastatic enzyme in the duodenal glands of the horse, ox, 

 pig and rabbit, but no proteolytic or rennin enzyme. 



The Secretion of Lieberkuhn's Glands. The secretion of these glands 

 has been studied with the aid of a fistula in the intestine according to the 

 method of THIRY and VELLA or of PAWLOW. According to BOLDYREFF 2 , 

 in dogs with an empty stomach a scanty secretion lasting about 15 min- 

 utes occurs at regular intervals for about two hours. According to this 

 experimenter, during gastric digestion the juice is periodically but less 

 abundantly secreted as the time interval is much longer, namely three, 

 four to five hours. Otherwise it is generally admitted that the partaking 

 of food causes the secretion, or if this is continuous, as in lambs (PREGL), 

 it increases the secretion. The researches of DELEZENNE and FROUIN 



1 Griitzner, Pfliiger's Arch., 12; Glaeesner, Hofmeister's Beitrage, 1; Ponomarew, 

 Biochem. Centralbi., 1, 351; Abderhalden and Rona, Zeitschr. f. physiol. Chem., 47; 

 Scheunert and Grimmer, cited in Bioch. Centralbl., 5, 673. 



2 Thiry, Wien. Sitz.-Ber., 50;. Vella, Molleschott's Untersuch., 13; Boldyreff,. 

 Zeitschr. f. physiol. Chem., 50. 



