SACBKOOD. 



19 



are not infectious. The status of the virus in this stage is not defi- 

 nitely kncwn, but the facts thus far obtained indicate that it is 



probably dead. 



Fourth Stage. 



The brown color of the larval remains has further deepened, the 

 anterior third being much darker as a rule than the other two-thirds. 

 The marked evidence of drying now present might be said to charac- 

 terize this stage. 



Anterior third. — ^The color is a veiy deep brown, often appearing 

 almost black. As a result of drying, the apex of this conehke third 



Fig. 20.— Fourth stage: Eemains of larva 

 dead of sacbrood. (Original.) 



is often nearer the roof of the cell in 

 this stage than in the preceding one. 

 As a result it has also been drawn 

 inward from the mouth of the cell. 

 The surface markings seen in the 

 normal larva are in this stage (fig. 

 20; PI. II, k) of decay almost obhter- 

 ated through the wrinkling of the 

 smiace, due to drying. 



Middle third. — This third is de- 

 cidedly brown, but lighter in shade 

 than the anterior third. The ventral surface (fig. 21; PI. II, q) is 

 shghtly concave from side to side. The segmental markings are still 

 to be seen, but are not at all prominent. The notched lateral mar- 

 gins extend upon the side walls of the cell. The subcuticular fluid 

 so noticeable in some of the earlier stages has disappeared through 

 evaporation. The effect of drying is' very noticeable, causing a 

 marked wrinkling of the surface. 



Posterior third. — The posterior third (PI. II, q) may or may not be 

 darker than the middle third, but it is not darker than the anterior 



Fig. 21.— Fourth stage: Eemains of .larva dead 

 of sacbrood, ventral view. ( Original. ) 



