88 HISTORICAL NOTES ON BEE DISEASES. 
well defined. When stained by Neisser’s method, a few show polar bodies (meta- 
chromatic granules). Involution forms, many of which grow to a large size, appear 
rapidly, and are very abundant after forty-eight hours’ growth. In broth at 37° C.a 
cloudy growth is first formed, but later the medium becomes clearer, and a consid- 
erable yellowish, flocculent deposit is produced. A surface film is usually seen after 
a few days’ growth, and may be very marked. If the tube is shaken, the film sinks, 
or is broken up, but another forms. The bacilli resemble those found on gelatin cul- 
tures. No acid or gas is produced in media containing glucose, lactose, en cet 
dulcite, mannite, maltose, dextrin, or glycerine. 
Pathogenic Properties.—A single infection experiment was made with a culture of 
this bacillus. A healthy stock of bees was placed in a hive ina green-house. Aftera 
few days all the openings were closed with muslin, and the bees fed on syrup. When 
the bees had become accustomed to this treatment, broth cultures of the bacillus were 
mixed with the syrup. Within a few days considerable numbers had died, and speci- 
mens of apparently diseased bees showed the bacilli in their chyle stomachs, which also 
showed the fragile condition found in naturally infected bees. Distention of the colon 
could not be taken as a diagnostic point, as this condition was found to be present in 
healthy specimens of this stock taken from the hive before the experiment was started. 
The majority of the bees showed no signs of disease a week after feeding was com- 
menced. 
The results of the anatomical and bacteriological studies of this 
disease by Malden are clearly set forth in the following quotation 
from his paper: 
Anatomically the majority of diseased bees show great distention of the colon, and 
a fragile condition of the chyle stomach. In many obtained from diseased stocks, 
and apparently suffering from the disease, distention of the colon is absent. All the 
organs, except those just mentioned, are normal. Healthy bees confined to their 
hives for a few days very closely resemble diseased bees in regard to the condition 
of their intestinal canals. It is impossible, therefore, both from the clinical and 
anatomical points of view, to diagnose whether any given bee is suffering from the 
disease or not. 
Histologically the chyle stomach appears to be the only organ affected, ane bac- 
teriologically plague-like bacilli were frequently encountered in it, in some cases 
apparently within the epithelial cells. These bacilli were not found either in the 
brood of diseased hives or in the chyle stomachs of healthy bees. For these reasons 
I am inclined to regard these organisms as the cause of the disease. I am, however, 
well aware that I have not fully established their relationship to the disease, since 
I have not been able to demonstrate them in every case either microscopically or by 
culture, or to find, except in very advanced cases, any very definite lesions con- 
stantly associated with their presence. I feel that my inability to discover any 
means of cultivating the organism with certainty even from chyle stomachs, in which 
it was present in abundance as shown by microscopical preparations, constitutes the 
most serious difficulty in establishing its relationship to the disease. By their mor- 
phology alone, few pathogenic bacteria can be recognized, since morphologically 
indistinguishable, but non-pathogenic, organisms are frequently encountered. Con- 
sequently, until some satisfactory cultivation methods have been discovered, the 
bacteriological diagnosis of this organism must in most cases remain in doubt, for 
organisms simulating it in morphology probably exist. 
Concerning this disease and its cause the following points are to 
be emphasized: 
1. Malden found the disease which Imms reported still present on 
the Isle of Wight. 
