Plate VI.
Tenebrio molitor.
Figs. 169-170. Equatorial plates of spermatogonial mitosis, showing 19 large and 1 small chromosome.
171-175. Condensation stage, bouquet stage, spireme stage, and rather rare tetrad stage of young spermatocyte.
176. Bivalent chromosomes, with longitudinal split; small chromosome shown at s.
177. Bivalent chromosomes condensed into a close spireme.
178-179. Bivalent chromosomes separating for mitosis. The unsymmetrical pair shown in fig. 179.
180. Prophase of first maturation mitosis, showing the unsymmetrical pair and the tetrad nature of the symmetrical pairs.
181. Prophase of same mitosis, showing symmetrical and unsymmetrical pairs, as in figs. 178 and 179.