Further Experiments, cf-c. By Dr. R. L. Maddox. 951 



at once see, supposing it to be in any way pathogenic, how it may 

 perhaps become a serious source of injury to animals, birds, and 

 perhaps fishes. I am not aware of any remarks having been made 

 upon the diminution of the domesticated feathered tribe during 

 severe cholera epidemics. It would, if possible, be a point well 

 worth ascertaining. 



The Eristalis, though so hardy, did not seem as fit an insect 

 for the experiments as the blow-fly. Investigations were made on 

 some other insects, as young wasps, house-flies, and what I believe 

 were mason bees, but they all too readily succumbed to captivity, 

 and offered nothing satisfactory. I am well aware of the weak 

 points in these investigations, and of the various sources of error 

 in furnishing other bacteria than the curved bacilli. The sugar 

 was not sterilized ; the body of the insect under the constant toilet 

 attentions might provide a variety of bacteria, which falling on, or 

 being carried into the dejections, or deposited on the square of 

 glass, might easily contaminate the rest, and vitiate the conclusions 

 on some points, but not, I believe, in any serious way disturbing 

 those relating to the curved bacilli. 



Some may object to so much reliance being placed on the use 

 of the Microscope. It was the readiest, if not the most perfect 

 means of distinguishing the commas, and afforded much guidance 

 in the many hundred examinations made, and would in any case of 

 suspected infection from such a source be probably the first if not 

 the only aid used. The micrococci from their abundance were a 

 great source of trouble in these examinations, and in the cultures. 

 ►Staining the sugar offered the chance of the dye proving hurtful 

 to the microbes, but I fear it was also detrimental to the female fly 

 that died. The mode of capture of the insects was by bringing 

 suddenly a short wide-mouthed bottle, held in the right hand, over 

 the insect at rest, and closing the mouth of the bottle with a folded 

 handkerchief held in the left, the fly being turned out afterwards 

 under the tumbler, its opening facing from the window. If the 

 insect escaped it generally flew at once to the window, when the 

 tumbler was placed over it and a clean piece of stout note-paper 

 passed beneath it, and then carried to the saucer. Thus the 

 insects were not touched by the hands. The used squares of glass 

 and vessels were flushed with or placed in methylated alcohol, 

 allowed to dry, and then cleansed with scalding water and washing 

 soda. The waste cultures were burnt. The general magnifica- 

 tion used was from 450 to 650 diameters, and all doubtful points 

 further elucidated by the use of a 1/1 (J water immersion or 1/12 

 homogeneous immersion objective. The fine granular debris often 

 needed considerable dilution. The examinations were long and 

 tedious. 'I'he insects were generally watched to be sure that they 

 had fed off any particular culture, which was blown on to the sugar 



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