Journal of Applied Microscopy. 



269 



malignant oedema, it will show a good growth not only along the line of inocu- 

 lation in the deeper layers of the agar, but also in the liquid on the surface. 

 This liquid is apparently is direct contact with the air. It is possible, however, 

 that the carbonic acid and other gases given off by the organism displace the 

 air from the tube and allow thus a growth to take place. 



A better and more useful procedure than the above is to employ gelatin con- 

 taining two per cent, of glucose and colored with litmus. The ordinary test- 

 tubes containing this material are inoculated and placed direct in the incubator 

 at 37°. Although the gelatin melts and apparently there is free access of air, 

 yet abundant growths of all of the anaerobic bacteria can thus be obtained. 

 The viscosity of the liquid undoubtedly prevents the access of air. It is evident 

 that the author's method as just given is the simplest possible procedure. The 

 cultures are readily accessible for examination, and, moreover, they retain their 

 vitality longer than cultures on agar or in bouillon. 



MICROBIC ASSOCIATION. 



When a strongly aerobic germ, such as the Micrococcus prodigiosus or the 

 Proteus vulgaris, is inoculated into a tube of bouillon, and if at the same time an 

 anaerobic organism is planted, it will be found that both bacteria will develop. 

 Apparently the aerobic form consumes the oxygen in the immediate neighbor- 

 hood of the anaerobic organism and thus allows the latter to develop. Such 

 ''cultur^es are intensely virulent. Conditions of this 

 kind not only favor the growth of anaerobic bacteria 

 in the soil, .but are known to bring on disease. 

 Tetanus or lockjaw is induced in this way as a 

 result of mixed infection. 



The various forms of apparatus indicated above, 

 and described in most of the text-books, are far 

 from being satisfactory. The use of special tubes 

 or of special plates, where a large number are to be 

 used, is a matter of considerable expense. The treat- 

 ment of each tube by itself and the subsequent seal- 

 ing involves a waste of time and is not altogether 

 free from danger. It is obviously desirable to make 

 use of the ordinary test-tubes and ordinary Petri 

 dishes. This can be done by means of the author's special apparatus, shown 

 in figures 2, 3 and 4. During the past six years this apparatus has been in 

 constant use in the Hygienic Laboratory of the University of Michigan. 



The bottle shown in Fig. 2 is intended for tube cultures. It is made in two 

 sizes (8x16 and lOx 20 cm. inside) for large and for small tubes. It is provided 

 with a hollow stopper, which should be not less than 4 cm. in diameter. There 

 are openings in the glass stopper corresponding to the two tubes in the neck of 

 the bottle. One of these openings has a glass tube attached which extends 

 down to within a short distance of the bottom. After the current of hydrogen 

 has passed through for some time, the stopper is turned at right angles, thus 

 effectually sealing the bottle. 



Fig. 2. 



