520 



Fig. 61. OmB^tidiuin of pupa twenty-four hours old (xl500). 



Fig. 62. The same, thirtj^-six hour pupa (xlSOO). 



Fig. 62a. The same, outer end (xloOO). 



Fig. 63. Outer part of ommatidium of fifty-two hour pupa 

 showing pigmentation of sheath cells (xloOO). 



Fig. 64. Ommatidium from eve of four and a half day pupa 

 ( XloOO). 



Fig. 64a. The same, outer end (xloOO). 



Fig. 64b. Pigment cell from the same (xl500). 



Fig. 64c. Section through vitreous cells of same (xlSOO). 



Fig. 64d. Section through terminations of several omma- 

 tidia at same stage (xlSOO). 



Fig. 65. Fresh pupa, anterior half, to show tracheal vessels 

 (x40). 



Fig. 66. Section of ocellus in two-celled stage, from the larva 

 in first instar (xlOOO). 



Fig. 67. Section through developing ocellus from the fresh 

 pupa (xlOOO). 



Fig. 68. The same, twelve hours later (xlOOO). 



Fig. 69. The same, from thirty-six hour pupa (xlOOO). 



Plate XXI. 



The same, three-day pupa (xlOOO). 



Vertical section through median ocellus of imago 



A single sensory cell from the same (x2300). 

 Pigment cell from fifty-two hour pupa. 

 Vertical section through the eye and perioptic mem- 

 brane, from larva about to pupate (xl200). Several cells of the 

 perioptic membrane are shoAvn. The three types of processes are 

 clearly seen, especially the fibrous processes, which penetrate into 

 the brain. Into these the nerve cells are seen migrating, and 

 one, on the extreme left, has communicated with an ommatidium. 



Fig. 75. The same, four hours later, showing nerve cells 

 adhering to the "neurolemmal'' cells of the perioptic membrane 

 (x200q). 



Fig, 76. A simple respiratory cell from the abdomen of 

 larva eight hours before pupation. An oenocyte is also seen, pre- 

 senting vacuoles, evidently a sign of degeneration (x500). 



Fig. 77. Vertical section through right side of head of larva 

 eight hours after defaecation (x230). 



Plate XXII. 



Fig. 78. Section through left side of liead of defaecating 

 larva (x230). 



Fig. 79. Vertical section through developing eye of thirty- 

 six hour pupa (x400). 



Fig. 80. Vertical section tln-ough right side of head of four 

 and a half day pupa (x230). 



Fig. 81. Central (nuclear) region of giant respiratory cell, 

 from larva sixteen hours after defaecation (xlOOO). 



Fig. 82. Tracheoloblast growing out from regenerating 

 tracheal trunk — defaecating larva (xlOOO). 



Fig. 83. Epithelium of longitudinal tracheal vessel under- 

 going histolysis (xlOOO). I^ucocyt^s are- attacking the dis- 

 integrating cells. 



Fig. 



70. 



Fig. 



71. 



(X2O0O). 





Fig. 



72. 



Fig. 



73. 



Fig. 



74. 



