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Wm. S. Marshall, 



three parts; ov, the middle piece; odt, the proximal portion which later develops 

 into the oviduct. Numbers in the tubules represent positions from which 

 correspondingly numbered cells or nuclei have been taken. 

 The arrow points towards the distal end of the tubule. 



Plate XII. 



Fig. 1. Section showing part of a gonad, from an embryo 1,35 mm long. 

 The reproductive organ is here a synctium with the contained nuclei all of the 

 same strueture. x 1600. 



Fig. 2. Enlarged view of a nucleus from the same gonad. x 2500. 



Fig. 3. The proximal half an ovarian tubule from a larva 2,6 mm long. 

 X 1600. 



Fig. 4. One of the largest cells from the same tubule. x 2500. 



Fig. ö. Dividing cell from the gonad of a larva of about the same age 

 as figure 3. x 2500. 



Fig. 6. Ovary A. Ovarian tubule from a larva 7 mm; length of tubule 

 0,275 mm. x 100. 



Fig. 7. Two cells from ovary A; a, cell from the proximal; b, cell from 

 the distal part of the tubule. x 1600. 



Fig. 8. Group of six attached cells, from ovarian tubule of a larva 13 mm 

 in length. x 850. 



Fig. 9. Ovary B. Ovarian tubule from a larva 16,5 mm long; length of 

 tubule 0,6 mm. x 100. 



Fig. 10. Cell from position 10 in ovary B. x 1600. 



Fig. 11. Another cell from the same ovarian tubule, taken from place at 

 number 11. Line to right represents wall of tubule. X 1600. 



Fig. 12. A third cell from the same tubule, taken from position 12. 

 X 1600. 



Fig. 13. Ovary C. An ovarian tubule from a füll grown larva which has 

 just enclosed itself for pupation. x 100. 



Fig. 14. A small part of ovary C near the distal end, showing three cells 

 which reach across the tubule; from place designated by number 14 in preced- 

 ing figure. x 1600. 



Fig. 15. Young oöcyte nucleus, from point 15 in ovary C. x 1600. 



Fig. 16. Group of cells from same ovary, taken from place indicated 

 by 16. X 1600. 



Fig. 17. A cell from position 17 in ovary C. x 1600. 



Fig. 18. Ovary D. The proximal portion of an ovarian tubule from a 

 wasp after pupation has begun. Bracket T, represents that part which is 

 enlarged in the following figure. x 100. 



Fig. 19. Portion of ovary D shown in preqeding figure by bracket T. 

 This is the proximal end of the distal portion of the tubule, and the distal end 

 of the median portion. X 500. 



Fig. 20. A cell, median in position, from point 20 of figure 19. x 2000. 



Fig. 21. A nucleus from a nearby marginal cell, from place 21 in figure 19. 

 X 2000. 



Figs. 22, 23 and 24. Three primitive nurse-cells all taken from figure 19 

 at places with corresponding numbers. x 2000. 



Fig. 25. Nucleus of a young oöcyte taken form position 25 in figure 18. 

 X 2000. 



