32 Investigations on the Life-History 



contained in the contents. A low aridity and practically an extinct 

 power of peptic digestion coincides with the presence of large numbers 

 of micro-organisms. The fish from the stomachs of which no organisms 

 were cultivated were all caught in October at the river mouth, and 

 possessed a marked power of digestion and a high degree of acidity. 

 The three in which moulds alone were found also came from the 

 estuaries during March. The three with a few bacteria in addition to 

 moulds were caught at the same time of the year, but gave a higher 

 digestive activity. Of the seven in which innumerable bacteria were 

 found one was caught at the mouth in March, the others in Jury 

 and August, two in the upper waters, five at the river mouths. 



The peptic digestion of the gastric extract was tested in five of the 

 fish from stomachs of which the Bacillus coli communis was obtained. 

 The extract was inactive in all, and showed only a trace of acidity. In 

 No. XII., 1895, the growth from the stomach proved to be a pure 

 cultivation of this organism. 



Apart from the actual demonstration of the absence of food from the 

 stomach cavity in all the salmon examined, the slight acidity and small 

 digestive power of the extracts of the gastric mucous membrane recorded 

 lead to the conclusion that the fish both in the estuaries and in the 

 rivers were in a fasting condition. 



(d) The Nature of the Acid present in the Gastric Extract. 



Fifty ccin. of rectified spirit in which the chopped-up stomach of 

 Fish No. XXXIX., July, 1896, had been immersed, were distilled. 



The first 40 ccm. which distilled over showed an acidity equal to 

 0-073 per cent, as HC1, but no hydrochloric acid was present. 

 Ufielmann's carbolo- ferric reagent was turned to a greenish-yellow hue. 

 The next 6 ccm. were neutral. 



The remainder, 4 ccs., was shaken up with ether, and then an excess 

 of distilled water added. The water was removed from the ether by 

 means of a separation funnel. It amounted to 163 ccm. 100 ccs. 

 gave an acidity of '00438 per cent, with no free hydrochloric acid, both 

 the phloroglucin-vanillin and the dirnethyl-amido-azo-benzol tests 

 proving negative. On the addition of decinonnal hydrochloric acid to 

 24 ccm. in the presence of dimethyl -amido-azo-benzol 110 reaction occurred 

 until 0'6 ccm. had been run in, or until 0*082 per cent, of the acid had 

 combined with the substances present, which were previously free from 

 such an acid combination. The addition of nitrate of silver in the 

 presence of nitric acid to the 100 ccm. tested for acidity caused a 

 precipitate weighing after incineration 0'025 gramme, 0-013 grammes 

 of which was soluble in nitric acid, leaving 0*012 grammes of chloride 

 of silver. This is equal to 0-00305 grammes of hydrochloric acid, or the 

 chlorine present was 0-003 per cent., while 0-013 grammes of silver, 

 equal to 0-0204 grammes of silver nitrate, were combined to organic 

 bodies. The ether contained 0-00219 per cent, of acid, and on 

 evaporation of part of the solution and addition of water Ufielmann's 

 reagent was discoloured, leaving a very slight yellow tinge. 

 llesult, 50 ccs. 



46 ccs. distilled ; acidity equal to 0-0292 grammes HC1. 

 4 ccs. remaining ; 0-00819 ., 



Watery extract 163 ccm., acidity equal to 0-0071 grammes HC1. 



Ether extract 50 ccm., 0-00109 



Acidity of distillate, 0-0634 per cent. 



Acidity of remainder, 0-2047 per cent. 



Acidity of total 50 ccm., 0-07478 per cent, or 0-03739 gramme of acid. 



