100 ON THE ANATOMY OP THE PLY. 



Section XIX. The Folliculate or Ductless Glands. 

 PLATE IX., Fms. 2 AND 3. 



The ductless glands are most abundant in the abdomen on 

 the dorsal surface of the viscera, near the dorsal vessel, and 



DESCRIPTION OF PLATE IX. 



Fig. 1. The dorsal vessel, x 12 diam. 



Fig. 2. A portion of one of the folliculate glands from the abdomen 

 of a young fly, x 25 diam. 2 a, a portion of the same, x 100 diam. 

 2 6, a portion of the same, to show the ultimate distribution of the 

 tracheae and the cellular contents of the follicle, x 600 diam. 



Fig. 3. A portion of one of the folliculate glands from the side of the 

 dorsal vessel of the larva. X 40 diam. 



Fig. 4. The epitreme of one of the abdominal spiracles, x 100 diam. 

 Fig. 5. The internal generative organs of the male, x 15 diam. 



Fig. 6. The four posterior abdominal segments of the male, showing 

 the loop and pouch in the position it occupies when the four segments are 

 partially exserted. The dotted line indicates the position of this part 

 when the segments are fully exserted. x 10 diam. 



Fig. 7. A diagrammatic section of the last two segmeuts of the abdo- 

 men in the male, in which a represents the penis, b the ventral plate of 

 the penultimate segment, and c the dorsal portion of the last segment. 

 X 10 diam. 



Fig. 8. The last two segments of the abdomen of the male, with the 

 ejaculatory organ and duct seen laterally, x 45 diam. 



Fig. 9. The same seen from below, x 36 diam. 



Fig. 10. The penis, with its palpi. X 60 diam. 



Fig. 11. The apod&ne of the penis, viewed from above. X 50 diam. 



Fig. 12. The extremity of the penis, x 100 diam. 



Fig. 13. The ejaculatory organ, x 100 diam. 



Fig, 14. Spermatozoids. X 100 diam. 



