BACTERIOLOGY OF SARDINES 189 



SESSIONAL PAPER No. 38a 



of nutrient broth eliminated to a minimum any risk due to the presence of 

 muscle sugar. It may be mentioned that repeated tests for the presence of 

 muscle sugar in the peptone used gave a negative reaction based on the absence 

 of acid and gas; the tubes being inoculated from an active strain of the B 

 coli group. 



Prior to the inoculations of the series, peptone broth tubes were inoculated 

 from agar slopes, and incubated at S7° C. After 18 to 24 hours, usually about 

 20 hours, the whole series of media would be inoculated with the broth from 

 a 1 cc. pipette; 2 to 3 drops of culture to each tube. Slopes of solid media were 

 streaked with a standard 3 mm. loop platinum needle. The number of tubes 

 involved and the amount of test substances necessitated have been considerabl* 

 throughout the work, and to insure economy of expense and time, strictly quan- 

 titative estimations of the gas evolved have not been carried out other than by 

 means of the Dunham tube. In view of the method noted above, however, the 

 results are truly comparative throughout. Moreover, for the particular pur- 

 pose of the present work the essential point to be decided regarding the ferment- 

 ation of the test substances to gas is this — does a particular culture produce 

 gas, or does it not produce gas? It is not only of considerable interest, but of 

 much practical and classificatory value to know whether the amount of gas 

 produced in a given time at a given temperature from a given substance is great 

 or small. Such information can be comparatively well shown by the use of the 

 Dunham tube. 



Indol Production. — The tubes to be tested for Indol were incubated at 37° C. for 7 

 days ; the Bohme Ehrlich test being used. 



Reduction of Nitrates. — The Giltay solution was tested after 3 to 4 days incubation at 

 37° O., for the presence of nitrites. The sulphanilic acid and a-naphthylamin 

 reagents were used. 



Voges Proshauer Reaction. — After 48 to 72 hours incubation at 37° C. the culture 

 tested with a strong solution of KOH. The test if positive has usually shown 

 the typical eosin shade in the upper layers, within 2 hours at room temperature. 



Methyl Red Reaction. — Determined after incubation at 37° C. for 48 to 72 hours. 



Cans of Sardixe?-. 



General Description. Appearance of Cans and Conditions of Contents. 



Owing to the varieties of " brands " of sardines produced by the canning fac- 

 tories, the various methods of packing adopted, and the different substances utilized for 

 the giving of flavour and consistency to the finished product, it is not possible other 

 than in a general way to described the conditions met with in my examinations. 



Normal cans. — In outward appearance there is a complete absence of any " bulg- 

 ing"; the top and bottom are either quite flat or almost imperceptibly concave. On 

 shaking, there is no " rattle " and scarcely any movement of the contents can be 

 heard. When opened with the cutter, there is no expulsion of air or gas, with little 

 if any exuding of the oil or other material used in the process of packing. 



The contents are firm, not macerated, and often white in colour; this last, how- 

 ever, depending to some extent upon the materials used in the packing. The smell is 

 mildly characteristic of the fish, qualified by the variety of oil or tomato sauce used. 

 There is in appearance and odour a complete absence of putrefaction. The fish are 

 saturated to a greater or lesser extent with the oil, sauce, or other flavouring agents 

 used, but without losing their firm and solid condition. The oil or sauce will be seen 

 as a layer over and in the interspaces between the individual fish, rather than actually 

 within the bodies. 



