EXPERIMENT STATION BULLETINS. 



301 



Fig. 5. European foul-brood: a, j, k, normal sealed cells; b, c, d, e, g, i, 1, m, n, p, q, larvae affected by 

 disease; r, normal larva at age attacked by disease; f, h, n, o, dried down larvae or scales. Three times 

 natural size. From Farmers' Bulletin 442, U. S. Dept. of Agr., Bureau of Entomology. 



after the disease has progressed somewhat, due to the scattered cells of dis- 

 ease among the cells of healthy brood. Occasionally a larvae will be found 

 dead of the disease in capped cells, and then there will be punctured and sunken 

 cappings present. However, the disease attacks the larvae before they are 

 capped over as a general rule, and therefore not as many punctured and 

 sunken cappings are found as in American foul-brood. Usually there is 

 very little odor present. Exceptions to this rule have been reported, how- 

 ever, and it is probable that putrefactive organisms such as B. alvei, which 

 are present in the larval remains, are the cause of these odors. The writer 

 has examined microscopically several samples of foul-brood in which were 

 larvae containing the causal organisms of both American and European 

 foul-brood. Such dead larvae have unusual odors; some that of decaying 

 meat, others, the odor of rotting vegetables. These cases, although excep- 

 tions, emphasize the advisability of microscopic examination as a check to 

 gross diagnosis, especially of those samples which do not have all of the 

 regular symptoms. 



In the process of decay the skin of the larvae becomes tender and easily 

 broken, much the same as in American, but at no time is there the ropiness 

 of the decayed material that is found in American foul-brood. Just before 

 the decayed matter dries down into the scale the material is sometimes 

 stringy and more or less granular, but does not possess any of the elastic 

 qualities of American foul-brood. During the first stages of decay the con- 

 tent of the body is watery in consistency. The tracheae of the larvae fre- 

 quently stand out as white lines resembling spokes in a wheel. This char- 

 acteristic may remain after the scale is formed and is one of the ways of dis- 



