PRE8ENT STATUS OF INVESTIGATION OF BEE DI8EASE8. 3] 



dwell od ;ii length, we must pass on to the further consideration of this par 

 ticular organism. The Brs1 poinl to be determined in investigating Its relation 

 lo foul brood was whether this was a Dew bacillus, unknown except in connec 

 tion with tins disease of bees, or whether ii was a more or less well known 

 form. To ascertain this poinl with regard to micro-organisms the microscope 

 is of little use; recourse musl be bad to the study of their life history, more 

 especially to their peculiarities of growth on different soils. Of all tin- ma 

 terials employed ;is cultivating media, Koch's gelatinized meat infusion is 

 the most useful for purposes of diagnosis. This is composed or an Infusion 

 of meal containing l to :: percent of pepton, i<> per cent gelatin, made neutral 

 hy carbonate of soda, and thoroughly sterilized. This material was first in 



troduced with the view of having ;i highly nutritive solid and ;it the sa 



time transparent medium on which to carry en pure cultivations, bul it was 

 soon found thai owing to the remarkably diverse ways in which different 

 micro-organisms grew in it. it could he used as a means or diagnosis of the 

 kind of organism, a means more certain than any other which we al presenl 

 possess. For purposes of diagnosis, as well as with the view or carrying on 

 pure cultivations, tins material is used in three ways. While the material is 

 still fluid a small portion is poured into a number of pure titles plugged with 

 cotton wool, sterilized, and allowed to solidify. A line platinum wire, heated 

 in a flame and allowed to cool, is dipped into the material containing I he 

 bacterium in question, and then, after the removal of the cotton-wool pin-, is 

 rapidly plunged down through the gelatin to the bottom of the tube and then 

 withdrawn. The plug is reinserted and the tube kept at a temperature suita 

 ble for the development of most forms of bacteria, bu1 not bigh enough to 

 melt the gelatin. If growth takes place at this temperature it occurs either 

 on the surface around the point of entrance of the needle, or along the needle 

 track, or in both places, and the appearance of the growth varies remarkably, 

 according to the different spocjes of micro-organisms studied. The second way 

 is t<> liquefy and pour out a little of the gelatinized material on microscopic 

 slides or on larger plates of -lass which have been sterilized by heat. These 

 plates are placed in -lass vessels containing moist blotting paper to prevenl 

 drying of the gelatin and to proteel them from the dust. After the gelatin 

 has solidified the purified platinum needle charged with the bacteria is drawn 

 rapidly over the surface of the gelatin. Bacteria are sown along the track, 

 grow there, and the whole can he placed under a microscope and the charac- 

 teristics of the growth studied with a low power. In the third mode a tube 

 of the gelatin mixture is inoculated with a very minute quantity of the bac- 

 teria. The tube is then placed in water at the body temperature to me!1 the 

 gelatin. When the material is melted, it is thoroughly shaken up to diffuse 

 the bacteria through it and. while still liquid, is poured out on sterilized glass 

 plates kept in n moist chamber, as in the former c.-ise. Solidification verj 

 soon occurs, and the bacteria being caught at various parts of the gelatin 

 grow there in the form of groups or colonies, which can he observed under the 

 low power of the microscope. I shall now describe the characteristics of the 

 Bacillus ni ri i when cultivated in these three modes. 



{a i 'iist-iuhi cultivations.- If an infected needle he plunged into a tube of 

 gelatinized neat infusion in the manner described above, growth occurs both 

 on the surface and along the needle track, on the surface the bacilli shool out 



in all directions from the poinl of entrance of the i die, forming a delicate 



ramifying growth on the top of the gelatin; the characteristics of this growth 

 will be presently described under b. Along the track whitish irregular shaped 

 masses appear, which slowly increase in size and run together, in a few day- 



