PRESENT STATUS OF INVESTIGATION OF BEE DISEASES. 33 
straight, but tend to curve, and at a little distance from the track they grow 
round so as to form a circle. From this circle, which may be formed of single 
bacilli, the process continues forming a fresh circle farther on. The bacilli in the 
circle increase in number till ultimately it becomes completely filled up, and we 
have a nodule consisting of bacilli in the course of the shoot. These shoots may 
also join one another, forming a curved anastomosis, and the gelatin in the 
immediate vicinity of the bacilli becoming liquid, a series of channels are 
formed in the gelatin containing fluid in which the bacilli swim backwards and 
iorwards. Later on parts of these channels become apparently deserted by the 
baciili, so that the circles look to the naked eye as if they were detached from 
the main track, but with a low power of the microscope the empty channels 
can be traced. 
It is impossible to give a proper idea of the appearance of the growth. The 
forms assumed are the most beautiful shapes I have ever seen, but they are 
yery numerous, always, however, retaining the tendency to ferm curves and 
circles; thus we have the explanation of the appearances previously described 
in the test-tube cultivations. 
(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 group of bacilli. 
This group 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 grow below 16° C. The best growth in gelatin is obtained 
at a temperature of about 20° C. They grow most rapidly in cultivating 
materials kept at the body temperature. Very few spores are formed at 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 
a slow oscillating movement. 
They grow rapidly at the body temperature in meat infusion with pepton 
and 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 that 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 grow 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, or only very imperfectly, in agar-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 _spores 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 grow very slowly indeed at the lower temperature. In order to get good 
growth it is necessary to keep the potato at the body temperature. 
In milk they grow well at the body temperature, and in a few days cease 
coagulation of the milk, which also assumes a yellowish colour and gives off 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, if indeed at all, acid. 
30547—No. 70—07 M——3 
