36 



Appendices to Second Annual Report 



There are several species in the stomach and intestine, but the investiga- 

 tion of the nature and affinities of these organisms requires separate 

 study. 



In order to extract the ferments, the mucous membrane of the part to 

 be investigated was first carefully freed from all impurities or traces of 

 food. It was afterwards minced very fine on a glass plate, and then sub- 

 jected for many hours or days to the action of the solvent. In the case 

 of glycerine, it seemed to me that a more powerful extract was obtained 

 more rapidly by bringing the glycerine into contact with the chopped-up 

 mucous membrane in its perfectly fresh state than when the mucous mem- 

 brane was subjected to the action of absolute alcohol for twenty -four 

 hours previously, as recommended by v. Wittich. Both extracts of the 

 stomach were active. I made several extracts of the part of the diges- 

 tive tract lying above the point where the pyloric sac leads from the 

 cardiac sac. This part of the canal includes the oesophagus and the upper 

 part of the cardiac sac, as can readily be determined by the microscopic 

 structure. In extracting this part with glycerine, weak spirit, boracic 

 solution, or chloroform, I always obtained an extract possessed of digestive 

 properties. The ferment is obtained, not from the oesophagus, which con- 

 tains no glands, but from the end of the cardiac sac continuous with the 

 oesophagus, and lying above the aperture of exit into the pyloric sac. 

 After the solvent had extracted the ferment, the solution so obtained was 

 filtered in order to get a clear fluid to work with. 



Having obtained a clear solution of the ferment, the next thing was to 

 test its activity upon some substances. As is usual with experiments on 

 artificial digestion, the ferment has to be diluted with an acid or alkaline 

 medium, as the case may be. In the case of the extract of the cardiac 

 and pyloric sacs, I used a solution of hydrochloric acid — 2 parts of the 

 acid in 1000 parts of water, and for the extract of the pyloric appendages 

 I used a 1 per cent, solution "of sodium carbonate. 



A flake of well-washed fibrin was placed in a test-tube containing a 

 solution of the ferment and a medium of appropriate reaction, and the 

 mixture was exposed to a temperature of 37°-40° C. After numerous 

 experiments, I found that the ferments of fishes, like those of mammals, 

 are most active at this temperature, although under normal conditions they 

 act at a much lower temperature. This observation agrees with that of 

 Krukenberg,* who found that a temperature of 37°-40° C. was, as a 

 general rule, most favourable for these experiments. 



In all cases control experiments were made by previously boiling the 

 solution of the ferment, which has the effect of destroying the ferments ; 

 so that in these experiments no effect was produced upon the fibrin. 



The presence of a diastatic ferment was tested for in the usual way 

 with a solution of starch, and after the mixture had been exposed for 

 some time to a temperature of 37°-40° C, the presence or absence of 

 sugar was ascertained in the usual way by boiling with Fehling's solution. 

 Control experiments were also made in each case by boiling the solution 

 supposed to contain the ferment, and testing the ferment fluid itself. 

 There is one point in testing for the presence of minute traces of sugar 

 which is of importance, viz., to add only a small amount of Fehliug's 

 solution ; in fact, the mixture should just show the faintest tinge of blue. 

 A trace of sugar may thus be detected which would not be observed if 

 too much Fehling is added. 



* UntcrsucJiungcn aiis dem physiologischen Institut. d. Univcrsitat, Heidelberg 

 ( \V. Kiibne), vol. i. p. 329. 



