46 Investigations on the Life-History 



Entries are made in Tables II. "and III. under the headings of 

 Tube I. and Tube II. of the number and character of the micro- 

 organisms grown from the three portions of the alimentary tract 

 investigated, the oesophagus, stomach, and intestine. At the end of 

 each of the four seasons into which the observations naturally fall, (1) 

 March, (2) May-June, (3) July and August., and (4) from September to 

 the end of the year, the approximate total number of growths is given, 

 followed by the average per fish. 



Similarly the total number of liquefying and non-liquefying organisms 

 and the number of moulds are noted. 



The results are graphically displayed in Charts I., II., and III. 



In Chart I. the average number of organisms grown in the first 

 roll-tubes is given for each season and for each section of the alimentary 

 canal. The unbroken line represents the figures relating to the ceso- 



gus, the broken line to those for the stomach, and the dot and dash 

 to the figures obtained from the intestine. 



The method of representing the colonies when present in too large a 

 number to admit of accurate computation has already been given. 

 Moulds are included among the non-liquefying series owing to the com- 

 paratively long period which elapses before they affect the solidity of 

 gelatine. , 



Chart II. has been constructed from the number of bacteria which 

 were grown at each season from the different sections of the digestive 

 canal, and which caused liquefaction of the gelatine medium. 



The general form of the curves corresponds to that in the preceding 

 Chart. The number of organisms grown from the esophagus exceeds 

 the number cultivated from the other two sections during the months 

 of July and August in a marked manner. The chief point of difference 

 between the figures for the organisms which liquefy gelatine and those 

 for the total number lies in the larger proportion which of the former 

 recorded as grown from the intestine. 



It necessarily follows that the converse is true of the mm -liquefy ing 

 organisms, and a glance at Chart III.' shows that fewer of these 

 organisms were grown from the intestine and a greater number from 

 the contents of the stomach. The figures for the oesophagus are practi- 

 cally the same in both cases. 



The Charts show that the number of organisms present in the 

 oesophagus exceeded those in the other sections of the alimentary canal 

 in the latter half of the year. In March the numbers grown from the 

 intestinal contents exceeded those from the stomach by an average of 

 12, and those from the oesophagus by 21. The numbers during this 

 month were very low, while almost no growths were obtained from any 

 of the second tubes. In fact, the total number of colonies which 

 appeared in the second tubes inoculated from the three sections of the 

 canals of seven fish only reached 35, or five colonies a fish, and 1 -6 colonies 

 011 an average in each individual section! Still fewer i growths were 

 obtained from the salmon caught in May and June, an average of only 

 two in each oesophagus, 11-7 in each stomach, and 7'2 in each intestine. 

 The second tubes show a slightly larger number than in March, due to 

 the number of moulds present in them. 



In the case of the fish captured in July and August, large numbers 

 of organisms were grown from each part :of the canal. ! A glance at 

 Chart I. shows that those cultivated from tlie contents of the oesophagus 

 are largely in excess of the numbers present in the stomach or intestine. 

 The numbers for the second tubes also show a great rise, except in those 

 from the intestine. In the later months of the year the colonies 

 grown fall below the numbers during Jujy and Augus^, but are still 

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