EXPLANATION OF PLATES 



Plate I 



Brood-combs containing larvse that are sick and others that are dead of Euro- 

 pean foulbrood, showing the Irregular appearance of the brood. About one-half 

 natural size. 



A. — The dead larv£e have all been removed. Some of the remaining larvse 

 are sick, others are not infected. The disease was produced by experimental 

 inoculation. 



B. — Many of the dead larvce have not been removed. The comb had been 

 out of the colony for a considerable period. The larvae that are quite young 

 showing abnormal position and appearance are not sick or dead of European 

 foulbrood, but are so as a result of the comb being away from the colony. 

 Disease was produced by experimental Inoculation. 



C. — ^The comb was taken from a colony in which the disease had appeared 

 in nature and not as the result of artificial inoculation. Before being photo- 

 graphed the brood-comb had been out of the hive for a few days. Aside from 

 the larvse which are dead of European foulbrood, other larvse present are dead 

 from lack of attention by adult bees — starvation, exposure, and other causes. 



Plate II 



A. — Live larva showing first symptoms of European foulbrood. The tur- 

 gidity is slightly less than in a healthy larva (D). 



B. — ^Live larva showing early symptoms of European foulbrood. The body 

 is more transparent than that of a healthy larva (D). Small opaque areas give 

 it a punctate appearance. 



C. — ^Larva dead of European foulbrood contained within a chitinous envelope 

 iilled with a watery-appearing fluid. 



D. — ^Healthy larva of the earliest age at which larvse die of European foul- 

 brood. Turgidity marked. 



E. — European foulbrood larva which may or may not be dead. Surface less 

 glistening than in healthy larvse. Marked turgidity lost. Prominence of tracheae 

 not increased. 



P. — Scale formed by drying of larvae dead at early age. Prominence of 

 tracheae marked. 



G. — View of healthy larva in normal position with roof of cell removed. 

 Larva turgid. Surface glistening. 



H. — ^Larva sick with European foulbrood. Lack of turgidity and increased 

 prominence of tracheae observed. 



I. — European foulbrood larva which may or may not be dead. Less turgidity, 



a relative dullness in the surface appearance, and punctate condition present. 



Similar to B. 



Plate III 



A. — Healthy lai;va immediately preceding the age at which the capping of the 

 cell is done. Dorsal surface turned toward the observer. The narrow trans- 

 parent area along the dorsal median line is prominent. 



B. — ^Larva dead of European foulbrood of the same age as A. The turgidity, 

 glistening surface, and transparent area are less marked. 



0. — ^Larva dead of European foulbrood partly coiled and partly endwise in 



cell. 



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