Chapter 4

99-100. First spermatocyte, equatorial plate.

101. Unequal heterochromosome pair from a metaphase.

102. First spermatocyte, anaphase; ordinary chromosomes stippled to show more clearly the metakinesis of the unequal pair.

103. Second spermatocyte, equatorial plates.

104. Second spermatocyte, prophase.

105-106. Abnormal giant spermatids, probably in process of degeneration.

_Euphoria inda_ (_Family Scarabæidæ_).

107. Equatorial plate of spermatogonium, 20 chromosomes. The 2 smallest are the unequal pair of heterochromosomes (_l_ and _s_).

108. Resting spermatogonium, showing plasmosome (_p_).

109. First spermatocyte, spireme stage.

PLATE XI.

_Euphoria inda._

FIGS. 110-111. First spermatocyte, prophases.

112-113. First spermatocyte, late prophase.

114-116. First spermatocyte, metaphase.

117. First spermatocyte, equatorial plate, _x_ the unequal pair.

118-120. First spermatocyte, anaphase.

121. First spermatocyte, daughter plates.

122. Second spermatocyte, prophase.

123. Second spermatocyte, equatorial plates.

124-125. Second spermatocyte, daughter plates of the two classes.

126-127. Second spermatocyte, anaphase.

128-130. Spermatids, _n_ the chromatin nucleolus.

_Blepharida rhois_ (_Family Chrysomelidæ_).

131-132. First spermatocyte, spireme stages, showing the heterochromosome group.

133-135. First spermatocyte, beginning of metakinesis.

136. First spermatocyte, equatorial plate, _x_ the unequal pair.

137. First spermatocyte, late anaphase, showing the heterochromosomes _l_ and _s_.

138. Second spermatocyte, equatorial plates.

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.

PLATE XII.

_Doryphora decemlineata_ (_Family Chrysomelidæ_).

FIGS. 151-152. Equatorial plates of spermatogonia, 36 chromosomes--35 large, 1 small.

153. First spermatocyte, synizesis stage.

154. First spermatocyte, synapsis stage.

155-158. First spermatocyte, spireme stages.

159. First spermatocyte, spireme segmented and split.

160-163. First spermatocyte, prophases.

164-171. First spermatocyte, metaphase.

172. First spermatocyte, anaphase.

173-174. First spermatocyte, equatorial plates.

175-176. First spermatocyte, late anaphase.

177. Second spermatocyte, equatorial plates.

178-179. Second spermatocyte, telophase, _a_{1}_, archoplasmic material.

180-186. Spermatids in different stages; _a_{1}_, archoplasmic material from first spermatocyte spindle, _a_{2}_ archoplasmic material from second maturation spindle.

_Spruce-borers_ (_Family Buprestidæ_).

187. First spermatocyte, metaphase.

188-189. First spermatocyte, equatorial plates of two species, 10 and 11 chromosomes.

190. First spermatocyte, anaphase.

191. Second spermatocyte, equatorial plates containing 9 large chromosomes and 1 small one.

192. Chromosomes from prophase of the first spermatocyte, all from the same cyst.

PLATE XIII.

_Adalia bipunctata_ (_Family Coccinellidæ_).

FIG. 193. Equatorial plate of spermatogonium, 20 chromosomes--19 large, 1 small.

194. First spermatocyte, spireme stage, _x_ the heterochromosome group.

195. First spermatocyte, metaphase.

196. First spermatocyte, equatorial plate.

197. Second spermatocyte, equatorial plates.

_Cicindela primeriana_ (_Family Cicindelidæ_).

198. Equatorial plate of spermatogonium, 20 chromosomes--19 large, 1 small.

199. First spermatocyte, spireme stage, _x_ the heterochromosome group.

200. First spermatocyte, prophase.

201. First spermatocyte, metaphase, _x_ the unequal pair in tripartite form.

202. First spermatocyte, showing metakinesis of the heterochromosomes (_l_ and _s_).

203. First spermatocyte, equatorial plate.

204. Second spermatocyte, equatorial plates.

205. Giant spermatocyte, spireme stage, heterochromosome group double the usual size.

206. Giant spermatocyte, prophase.

_Chlænius æstivus_ (_Family Carabidæ_).

207. First spermatocyte, spireme stage, showing the unequal pair associated with a large plasmosome.

208. First spermatocyte, metaphase.

209-210. First spermatocyte, beginning of metakinesis.

211. First spermatocyte, equatorial plate, 17 chromosomes.

212. First spermatocyte, anaphase, showing elongated centrosome and diverging univalent chromosomes.

_Chlænius pennsylvanicus._

213. First spermatocyte, spireme stage.

214. First spermatocyte, equatorial plate, _x_ the unequal bivalent.

215. First spermatocyte, late prophase.

_Galerita bicolor_ (_Family Carabidæ_).

216. Equatorial plate of spermatogonium, 30 chromosomes--29 large, 1 small.

_Anomoglossus emarginatus_ (_Family Carabidæ_).

217. First spermatocyte, growth stage, _x_ the odd chromosome.

218. First spermatocyte, prophase.

219-220. First spermatocytes, metaphase, _x_ the odd chromosome.

221. First spermatocyte, equatorial plate.

222. First spermatocyte, daughter plates containing 18 and 19 chromosomes, respectively.

223. Second spermatocytes, equatorial plates.

_Elater I_ (_Family Elateridæ, species not determined_).

224. Equatorial plate of spermatogonium, 19 chromosomes, _x_ the odd one.

225. First spermatocyte, spireme stage, _x_ the odd chromosome.

226. First spermatocyte, metaphase.

227. First spermatocyte, prophase.

228. First spermatocyte, equatorial plate.

229. Equatorial plate from egg follicle, 20 chromosomes, _x_{1}_ and _x_{2}_ the pair corresponding to _x_ in the spermatogonium.

_Elater II_ (_Species not determined_).

230. Equatorial plate of spermatogonium, 19 chromosomes, _x_ the odd one.

231. First spermatocyte, spireme stage.

232. First spermatocyte, prophase.

233. First spermatocyte, beginning of metakinesis.

234. First spermatocyte, equatorial plate, _x_ the odd chromosome.

235. A pair of second spermatocytes in metaphase, two chromosomes connected, _x_ the odd chromosome.

_Ellychnia corrusca_ (_Family Lampyridæ_).

236. Equatorial plate of spermatogonium, 19 chromosomes.

PLATE XIV.

_Aphrophora quadrangularis_ (_Hemiptera 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 _m_-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 11 and 12 chromosomes, respectively.

258. First spermatocyte, _a_ and _c_ daughter plates, each containing 11 chromosomes, _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.

PLATE XV.

_Aphrophora quadrangularis._

FIGS. 264-265. Second spermatocyte, telophase, showing chromatin nucleolus (_n_) and the products of division of the odd chromosome (_x_).

266. A spermatid containing the chromatin nucleolus (_n_).

267-268. Spermatids containing both the chromatin nucleolus (_n_) and the odd chromosome (_x_), _a_ the acrosome.

269. Equatorial plate from a somatic cell of a male larva, 23 chromosomes.

270. Equatorial plate of an oögonium, 24 chromosomes.

271. Resting nucleus of a young oöcyte before synapsis, showing two pairs of condensed chromosomes, corresponding in size to the _m_-chromosomes and the odd chromosome of the spermatocytes.

272-277. Sections of nuclei of oöcytes, showing one or more of these heterochromosomes, from safranin-gentian preparations.

278-279. Bouquet stage from iron-hæmatoxylin preparations, showing the heterochromosome bivalent (_x_).

_Cacoecia cerasivorana_ (_Lepidoptera_).

280. First spermatocyte, synizesis stage, showing 2 condensed chromosomes (_x_{1}_ and _x_{2}_).

281-282. First spermatocyte, synapsis stage.

283-284. First spermatocyte, growth stages.

285. First spermatocyte, prophase.

286-287. First spermatocyte, later prophases, showing the heterochromosome pair (_x_).

288. First spermatocyte, metaphase.

289. Second spermatocyte, metaphase.

290. First spermatocyte, equatorial plate.

291-292. Second spermatocyte, equatorial plates.

_Euvanessa antiopa_ (_Lepidoptera_).

293. First spermatocyte, equatorial plate.

End of Project Gutenberg's Studies in Spermatogenesis, by Nettie Maria Stevens