G BULLETIN 810, U. S. DEPARTMENT OF AGRICULTURE. 



ing the segments of the body become less prominent. As the process 

 of decay advances the yellowish hue changes, the color assuming a 

 brownish tone. The segmental markings are less prominent, while 

 the tracheae often become quite distinct, appearing as white lines 

 contrasted with the darker color of the larval remains (PL II, B). 

 Not infrequently at this time there will be seen a chitinous envelope 

 containing a watery-looking fluid in which is the larva proper (PI. 

 II, C ; PI. ly, A). The decay proceeds and the drying becomes evi- 

 dent. The larval mass settling upon the concave bottom of the cell 

 causes the upper surface of the mass to be depressed about the cen- 

 ter. At this stage the tracheae not infrequently are seen distinctly in 

 the drying mass. When the larval remains become dry they are 

 known as the scale (PL II, F). The scales do not adhere closely to 

 the cell and when removed are found to be thin and more or less 

 circular in outline. They are convex and smooth on the side which 

 was in contact with the bottom of the cell while the opposite surface — 

 the one which, while in the cell, was toward the observer — is slightly 

 roughened and concave. 



GEOTJP 2 



Larvae (PL III) showing symptoms of European foulbrood and 

 classed in this group have reached a sufficient size to fill the deepest 

 third or more of the cell. The yellowish tint appears in contrast to the 

 bluish white of the healthy larvae? (PL III, D, G) . Increased movement 

 may or may not be observed. Before and after death the remains 

 may assume one of a number of positions in the cell. Not infre- 

 quently a portion of the dorsal surface is turned toward the observer 

 (PL III, B). Usually through the transparent area along the me- 

 dian dorsal line a whitish or yellowish-white mass is to be observed. 

 This mass is within the stomach of the larva and contains a large 

 amount of bacterial growth (PL VIII, a, b, c) consisting very largely 

 of Bacillus ])lMton. Often before death this mass is seen to move 

 within the stomach in response to the peristalsis-like movements of 

 the body of the larva. 



At the time of death the larva usually occupies some unnatural 

 position, being more or less curled up and lying upon the floor of the 

 cell (PL III, C, E, F, H, I). Lessened turgidity, a relative dullness 

 of the surface appearance, and a yellowish tint are present. Not in- 

 frequently the two ends of the larva are directed more or less 

 toward the bottom of the cell and some portion of the dorsal surface 

 is toward the opening of it (PL III, E, H, I). Among the dead 

 larvae will be found some with one end directed toward the bot- 

 tom, and the other toward the mouth of the cell, the body occupying 

 a more or less spiral position against the side walls and floor of the 

 cell (PL III, F). 



