Chap. VI. 



DIGESTION. 123 



round the margins of the discs were a little inflected, and 

 the secretion collected on the disc was acid, but the exterior 

 tentacles were not affected. One leaf began to re-expand on the 

 fourth day, and all were fully re-expanded on the sixth. The 

 glands which had been in contact with the mucin were a little 

 darkened. We may therefore conclude that a small amount of 

 some impurity of a moderately exciting nature had been 

 absorbed. That the mucin employed by me did contain some 

 soluble matter was proved by Dr. Sanderson, who on subjecting 

 it to artificial gastric juice found that in 1 hr. some was dis- 

 solved, but only in the proportion of 23 to 100 of fibrin during 

 the same time. The cubes, though perhaps rather softer than- 

 those left in water for the same time, retamed their angles as 

 sharp as ever. We may therefore infer that the mucin itself 

 was not dissolved or digested. Nor is it digested by the 

 gastric juice of living animals, and according to Schiff* it is a 

 layer of this substance which protects the coats of the stomach 

 from being corroded during digestion. 



Pepsin.— M-Y experiments are hardly worth giving, as it is 

 scarcely possible to prepare pepsin free from other albuminoids ; 

 but I was curious to ascertain, as far as that was possible, 

 whether the ferment of the secretion of Drosera would act on 

 the ferment of the gastric juice of animals. I first used the 

 common pepsin sold for medicinal purposes, and afterwards 

 some which was much purer, prepared for me by Dr. Moore. 

 Five leaves to which a considerable quantity of the former was 

 given remained inflected for five days; four of them then died, 

 apparently from too great stimulation. I then tried Dr. Moore's 

 pepsin, making it into a paste with water, and placing such 

 small particles on the discs of five leaves that all would have 

 been quickly dissolved had it been meat or albumen. The 

 leaves were soon inflected; two of them began to re-expand 

 after only 20 hrs., and the other three were almost completely 

 re-expanded after 44 hrs. Some of the glands which had been 

 in contact with the particles of pepsin, or with the acid secre- 

 tion surrounding them, were singularly pale, whereas others 

 were singularly dark-coloured. Some of the secretion was 

 scraped off and examined under a high power; and it abounded 

 with granules undistinguishable from those of pepsin left m 

 water for the same length of time. We may therefore infer, 

 as highly probable (remembering what small quantities were 

 given), that the ferment of Drosera does not act on or digest 



♦ 'Le9ons phys. de la Digestion,' 1867, torn. ii. p. 304. 



