DIAGNOSIS OF BEE DISEASES. 9 



that on thrusting the forceps into the brown larval remain and 

 withdrawing them a portion of the decaying mas adhere and is 

 drawn out, often to a distance, of 3 or 4 inches. The viscidity is 

 often referred to by the term "ropiness" in beekeeping Literature. 

 In the rare instances in which young uncapped affected larvae a re en 

 countered the ropiness is less pronounced. 



(g) Odor. — The odor is characteristic and may be described as 

 unpleasant. Often it is feeble or absent altogether, probably ha\ ing 

 disappeared after the removal of the diseased brood from the hive. 

 Affected brood-comb will absorb other odors if given the oppor- 

 tunity, thus masking the original characteristic odor. Such dis- 

 appearance and masking of the odor has been observed where speci- 

 mens of diseased brood in combs from various sources had been 

 thrown together and allowed to lie about preparatory to being de- 

 stroyed (McCray, 1916). 



(A) Kind of brood. — It is affected worker-brood that is most often 

 encountered in American foulbrood samples, although drone-brood 

 is sometimes affected. 



(i) Scales. — The scales of American foulbrood are distinctive and 

 are characteristic of the disease. If they are present in sufficient 

 numbers the disease can be diagnosed from the gross appearance 

 alone. The lower cell walls can be easily illumined by tilting the 

 upper portion of the comb toward the observer, as previously de- 

 scribed. The scales appear extended along the lower cell wall, are 

 quite dark in color, and adhere closely to the floor and base of the 

 cell. Sometimes they adhere so closely as to break when an attempt 

 is made to remove them from the cell. Often a semblance of the 

 form of the pupa? is evident in the dried-down mass forming the 

 scale. Some of the mouth parts of the pupa? sometimes protrude 

 sufficiently to adhere to the roof of the cell. 



MICROSCOPIC FINDINGS. 



In considering the microscopic appearance of stained smears from 

 infected brood in this disease, there usually is only Bacillus laarvae 

 in the spore form to engage the attention of the observer. In some 

 instances, however, samples containing the disease in its earlier 

 stages are received and then Bacillus larvae in the rod or vegetative 

 form may be encountered. Such a sample usually is more difficult 

 to diagnose. To receive a sample in which some older larvae con- 

 taining spores of BadHkis larvae can not be found, however, is a 

 very rare occurrence. 



In a stained smear made from an infected larva and mounted in 

 water, the microscopic picture is rather characteristic. The most 

 striking feature of the mount is the large number of spores adher- 

 ing; to the cover glass, floating- with the current, or dancing free in 



