72 DESCRIPTION OF PLATES. 



PLATE XIV. 

 Aphrophora quadrangular is (Hemzptera homoptera). 



FIG. 237. Resting primary spermatogonium with lobed nucleus. 



238. Resting secondary spermatogonium, with nucleus staining much more 



deeply. 



239. Equatorial plate of secondary spermatogonium, 23 chromosomes. 



240. First spermatocytes, very early growth stage, x the odd chromosome. 

 241-243. First spermatocyte, later spireme stages, showing the odd chromosome (x) 



and a pair of w-chromosomes (m). 



244. Similar stage from a safranin-gentian preparation. 



245. First spermatocyte, split-spireme stage, x the odd chromosome, m the m- 



chromosome tetrad. 



246. Similar stage from a safranin-gentian preparation. 



247-248. First spermatocyte, condensation of chromatin granules to form tetrads in 



the linin spireme. 

 249. Later tetrad stage. 



250-251. First spermatocytes, metaphase from mercuro-nitric material. 

 252-254. Similar stages from Hermann material, showing longitudinal split in both 

 the bivalents, and the odd chromosome (x). 



255. First spermatocyte, anaphase. 



256. First spermatocyte, telophase. 



257. First spermatocyte, daughter plates containing u and 12 chromosomes, 



respectively. 



258. First spermatocyte, a and c daughter plates, each containing u chromo- 



somes, x the odd 'chromosome at a different level (b). 



259. Second spermatocyte, equatorial plates of the two classes. 



260. Second spermatocyte, metaphase. 



261. Second spermatocyte, anaphase. 



262-263. Second spermatocyte, daughter plates of the two classes. 



