EUROPEAN rOULBROOD. 29 



II, III, IV), the yellow hue of the larvae more recently dead, and 

 the brown shade of those longer dead, the irregidarity of the brood 

 (PL I), and the absence of a disagreeable odor. 



Not infrequently, however, the diagnosis is not so simple. During 

 recovery from the disease scales (PI. V, F, I) of larvae dying in 

 capped cells may be the only remains of diseased brood to be found, 

 all of the younger larvaj having been removed by the bees. These 

 scales^ are, as a rule, comparatively few in number and resemble 

 somwhat those of American foulbrood, but would rarely be mistaken 

 for those of sacbrood. In these cases a diagnosis can be made fre- 

 quently by a microscopic examination alone. Cultures, however, are 

 needed in some instances. 



Special attention is needed in cases of early infection and in other 

 instances where only a small amount of diseased brood in uncapped 

 cells is present (PI. I, A). The symptoms manifested by larva sick 

 or only recently dead of the disease furnish often the readiest and 

 most conclusive evidence of the presence of the disease. Larvae of 

 the age at which they comfortably fill the bottom of the cell exhibit- 

 ing increased peristalsis-like movements of the body suggest European 

 foulbrood. Increased transparency of larvae of this age (PI. II, B) 

 is also suggestive. The presence of a white or yellowish-white mass 

 within the stomach (midgut) as seen through the dorsal median line 

 of the body is strong evidence of the presence of the disease. If 

 on puncturing the body of larvae nearly dead or only recently dead the 

 contents of the stomach flows out as a fluid and more or less finely 

 granular mass, the fact furnishes further evidence of European foul- 

 brood. 



A symptom which is pathognomonic of the disease is to be seen in 

 larvae that have been infected somewhat more than two days, but 

 wherein the disease has not reached an advanced stage. The test 

 (15) involves the removal of the stomach contents, which con- 

 sist of a bacterial mass, together with a small amount of larval food 

 and a clear envelope (PI. VIII, a, b, c). The slight tension necessary 

 to remove the contents stretches the envelope and breaks the whitish 

 bacterial mass into a number of fragments. 



1 The number of larrse that die of European foulbrood In capped cells after assuming 

 the endwise position represents a very small percentage of the brood that dies of the 

 disease. These remains may be found in practically all colonies in which the disease has 

 been present for a suflaclently long period and in which a considerable amount of dead 

 brood has resulted. Before becoming dry they are somewhat viscid and are less easily 

 removed than are those of larvae dying at an earlier age. These and the scales resulting 

 from them are used In diagnosis principally (1) when the younger larvse sick or dead of 

 the disease have been removed, (2) when a demonstration of the presence of Bacillus alvei 

 Is desired, and (3) when both European foulbrood and American foulbrood infection is 

 suspected. Such a double infection has been encountered in the writer's experience very 

 rarely. In making diagnoses, therefore, after European foulbrood has been found in 

 the sample American foulbrood Is seldom looked for. 



