PRESENT STATU8 OF INVESTIGATION OF BEE DI8EA8ES. 38 



straight, i>ut tend to curve, and a1 a little distance from the track the} grow 

 round so as to form a circle. From this circle, which ma\ be formed of Biugle 

 bacilli, the process continues forming a fresh circle farther on. The bacilli In the 

 circle increase in Dumber till ultimately 11 becomes completely filled up, and we 



have a nodule consisting of bacilli in the course of the shoot. These si is n ; .i\ 



;ils<» join «»nc another, forming ;i curved anastomosis, and the gelatin In the 

 Immediate viciuitj of the bacilli becoming liquid, a series of channels are 

 formed En the gelatin containing fluid in which the bacilli swim backwards and 

 forwards. Later on parts of these channels become apparently deserted by the 



bacilli, so that the circles look to the naked eye .-is If they were detached fr 



the main track, bu1 with a low power of the microscope the empty channels 

 can be traced. 



it is impossible («» give n proper idea of the appearance <>f the growth. The 

 forms assumed are the mosl beautiful shapes l have ever seen, inn they are 

 very numerous, always, however, retaining the tendency to form curves and 

 circles: thus we have the explanation of the appearances previously described 

 in the test-tube cultival ions. 



(c) The appearances of the colonies on plates on which the mixture of 

 bacilli and gelatinized infusion has been poured out is also very characteristic. 

 The earliest appearance Of colonies is a small oval or round -roup of bacilli. 

 This -roup is not homogeneous in appearance under a low power of the micro- 

 scope, but lines indicating the bacilli are seen in it. It very soon becomes pear 

 shaped, and from the sharp end of the pear processes begin to pass out into 



the gelatin as before described. 



These bacilli do not -row below 16° ('. The best growth in gelatin is obtained 

 at a temperature of about 20° ('. They grow most rapidly in cultivating 

 materials kept at the body temperature. Very few spores are formed ,-n the 

 lower temperatures, but they appear rapidly and in large numbers at the body 

 temperature. I have several times observed bacilli containing spores swimming 

 about freely. The reaction of the medium is not of any great importance, but 

 a neutral medium is apparently the best. The bacilli swim freely in fluids with 

 :i slow oscillating movement. 



They -row rapidly at the body temperature in meat infusion with pepton 

 ami rendered solid by agar-agar, but the appearance of their growth is not 

 nearly so characteristic as in gelatin. This, indeed, is the case with most 

 bacteria, so thai agar-agar preparations, though very useful for carrying on 

 pure cultivations at the temperature of the body, are of little value for diag- 

 nostic purposes. They -row most rapidly on the surface of the agar-agar, 

 forming a whitish layer, but the shoots described above in the case of gelatin 

 do not occur, op only very imperfectly, in tgar-agar. Here the bacilli arrange 

 themselves apparently side by side, and, producing spores in this position, we 

 have as a result, after a few days' cultivation, long rows of -pores lying side 

 by side with here and there an adult bacillus. 



On potatoes they grow slowly, forming a dryish yellow layer on the surface. 



They -row very slowly indeed at the lower temperature. In order to gel g 1 



growth it is necessary to keep the potato at the body temperature. 



In milk they -row well at the body temperature, ami in a few days cease 

 coagulation of the milk, which also assumes a yellowish colour ami gives "if the 

 odour previously described. The coagulum is not firm, like that caused by the 

 Bacterium lactis, but is like a tremulous jelly, and may remain for a consider- 

 able time without the separation of any fluid, but ultimately it becomes liquid, 

 and after some months assumes the appearance of a dirty, brownish-yellow. 

 glairy fluid. It is very slightly, it' indeed at all. acid. 

 30547— No. 70— 07 m 3 



