SAOBROOD. 



15 



verse tracheae under slight magnification may be distinctly seen. 

 The narrow, somewhat transparent area present along the ventral 

 median line of the healthy larva is still to be seen in this stage of the 

 decay. The lateral and posterior margins are still deeply notched 

 and are frequently found to appear quite transparent. This appear- 

 ance is due to a watery looking fluid beneath the cuticular portion of 

 ■the body wall. 



Sometimes only the remnant of a larva (fig. 14; PI. II, ww) dead 

 of sacbrood is found in the cell. Such remnants vary in size. The 



Fio. 16. — Second stage: Dorsal view of an- 

 terior third of a larva dead of sacbrood. 

 (Original.) 



surface left from the removal of tissues 

 is somewhat roughened, indicating that 

 the removed portion has been taken 

 away piecemeal, and is more or less 

 transverse to the larva. 



Consistency of the larva in the first 

 stage. — ^The cuticular portion of the 

 body wall, which chiefly constitutes the 

 sac that characterizes the disease sac- 

 brood, is less easily broken at this time 

 than in the healthy larva. When the 

 body wall is broken the tissues of the 

 larva, which constitute the contents of 

 the sac, flow out. This fluid tissue mass is less milky in appea,rance 

 than that from a normal larva. The granular character of the con- 

 tents of the sac which is marked in later stages of decay is already in 

 evidence. By microscopic examination the granular appearance is 

 found to be due chiefly to fat ceUs. 



Condition of the virus in the -first stage. — When larvae of this stage 

 are crushed, suspended in sirup, and fed to healthy bees, a large 



Fig. li— First stage: Portion of a larva 

 dead of sacbrood, showing a more or less 

 transverse roughened surface from which 

 the bees have removed a portion of the 

 larva piecemeal. (Original.) 



