( 252 ) 



If the experiment bears upon the pepsin inch the pepsinogen of the 

 gastric mucous membrane, the agar columns which have been on it, 

 are cut fine and mixed with 3 cc. HCi of 0.4%. For this we use 

 cylindrical bottles with close fitting glass stoppers: they have a dia- 

 meter of 24 mm. and a height of 48 mm. Into these bottles we put 

 albumen columns prepared according to Mett's method. When these 

 have been in contact with the agar-suspension for 10 hours or more 

 at 37.5 C, we determine by measurement how much has been 

 digested ; then the albumen columns are placed in it again and the 

 measurements are repeated a few hours later. In each bottle we 

 generally had two albumen tubes. Perhaps it will be objected that 

 the presence of solid particles of agar-agar must impede the action 

 of the pepsin on the albumen. This proves not to be the case: in 

 the first place we observe that on all 4 sides of the 2 albumen 

 columns always about the same column of albumen has been digested, 

 which most likely would not be the case if now and then an agar- 

 particle prevented the entrance of the digesting fluid. And secondly 

 we noticed that when the experiment is made with a liquid, from 

 which the agar particles have been removed by filtration, the rate 

 of digestion is the same as when the agar particles were still in 

 the tluid. 



If (he experiment bears only upon the pepsinogen of the gastric 

 mucous membrane, we place alkalic instead of neutral agar-agar on 

 it, viz. a quantity of agar of 2°/ in Na, CO, of 3 p. mille. The 

 investigations of Langley') have shown that in this concentration 

 pepsin is decomposed by Na 3 C0 8 , pepsinogen on the olher hand not. 



It stands to reason that besides pepsin and pepsinogen, chymosin 

 and prochymosin will also be absorbed by the neutral agar-agar. 

 It was found indeed that the agar-mass had obtained the faculty of 

 coagulating milk. 



In a similar way as the gastric mucous membrane the intestinal 

 mucous membrane may be experimented upon. We found that the 

 neutral agar absorbs both enterokinase and erepsin. The quantity of 

 enterokinase present in the agar is determined by cutting fine the 

 agar, mixing it with water, filtrating, and bringing the extract thus 

 obtained, into contact with inactive juice of a fresh pancreas gland 

 and two albumen tubes. 



The attentive reader will notice that here no agar particles are 

 present at the digestion of the albumen as in the case of the gastric 



') Langley Journal of Physiology 3 1882 p. 253. 

 Langley and Edkins Ibid 7 1886 p. 371. 



