Studies in Spermatogenesis Volume I Part 2

'01. A study of the chromosomes of the germ-cells of Metazoa. Trans. Amer. Phil. Soc., vol. 20.

'01_a_. Further studies on the chromosomes of the _Hemiptera heteroptera_. Proc. Acad. Nat. Sci. Phila. 1901.

'04. Some observations and considerations upon the maturation phenomena of the germ-cells. Biol. Bull., vol. 6, no. 3.

MOORE, J. E. S., and ROBINSON, L. E.

'05. On the behavior of the nucleolus in the spermatogenesis of _Periplaneta americana_. Quart. Jour. of Mikr. Sci., n.

s., no. 192 (vol. 48, part 4).

PAULMIER, F. C.

'93. Chromatin reduction in the Hemiptera. Anat. Anz., vol.

14.

'99. The spermatogenesis of _Anasa tristis_. Journ. of Morph., vol. 15.

RuCKERT, J.

'92. Zur Entwickelungsgeschichte des Ovarialeies bei Selachiern. Anat. Anz., vol. 7, no. 4 and 5.

DE SINeTY, R.

'01. Recherches sur la biologie et l'anatomie des phasms. La Cellule, vol. 19.

STEVENS, N. M.

'03. On the ovogenesis and spermatogenesis of _Sagitta bipunctata_. Zool. Jahrb., vol. 18.

SUTTON, W. S.

'02. On the morphology of the chromosome group in _Brachystola magna_. Biol. Bull., vol. 4, no. 1.

'03. The Chromosomes in heredity. Biol. Bull., vol. 4, no.

5.

WALLACE, L. B.

'00. The accessory chromosome in the spider. Anat. Anz., vol. 18.

'05. The spermatogenesis of the spider. Biol. Bull., vol. 8, no. 3.

WILc.o.x, E. V.

'95. Spermatogenesis of _Caloptenus femur-rubrum_ and _Cicada tibicen_. Bull. Mus. Comp. Zool. Harvard Univ., vol.

27.

'96. Further studies on the spermatogenesis of _Caloptenus femur-rubrum_. Bull. Mus. Comp. Zool. Harvard Univ., vol.

29.

'97. Chromatic tetrads. Anat. Anz., vol. 14.

'01. Longitudinal and transverse division of chromosomes.

Anat. Anz., vol. 19, no. 13.

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.