139-140. Second spermatocyte, daughter plates of the two classes.
Silpha americana (Family Silphidæ).
141. Equatorial plate of spermatogonium, 40 chromosomes—39 large, 1 small.
142. Resting nucleus of spermatogonium, showing 2 plasmosomes (p).
143-144. First spermatocyte, spireme stage.
145. First spermatocyte, prophase.
146-147. First spermatocyte, metaphase.
148. First spermatocyte, equatorial plate.
149. Second spermatocyte, equatorial plates.
150. Second spermatocyte, showing metakinesis of the small chromosome.