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DESCRIPTION OF PLATES.

[The figures of plates I-VI were all drawn with Zeiss oil-immersion 2 mm., oc. 12, and have been reduced one-third; those of plate VII with oc. 8, not reduced.]

PLATE I.

_Termopsis angusticollis._

FIGS. 1-3. Resting nuclei of spermatogonia, showing division of nucleolus.

4. Equatorial plate of spermatogonial mitosis, 52 chromosomes.

5-6. Young spermatocytes, showing division of nucleolus.

7. First maturation spindle, and two nuclei (6 and 8) in same cyst.

8-10. Skein-stage--so-called synapsis-stage.

11-14. Bouquet-stage, showing two nucleoli, centrosome (_c_) in fig. 11, and loops made up of fine, then coa.r.s.er granules.

15-17. Stage following preceding; loops straightened out and extending in various directions through nucleus.

18. _a_, Chromosomes much shortened and longitudinally split; _b_, chromosomes contracted to form diamond-shaped figures.

19. Stage between 18_a_ and 18_b_.

20. Stage between 19 and 18_b_.

21. Stage similar to 18_a_, one chromosome in double diamond form.