INVERTEBRATA, CRYPTOGAMIA, MICROSCOPY, ETC. 637 



vesicles form six small outgrowths on the septa of the ninth- 

 tenth, tenth-eleventh, and eleventh-twelfth segments, respectively ; 

 the anterior pair grow forward so as to project into the ninth ring, 

 tlie second grow backward into the eleventh, and the third into the 

 twelfth ring ; " the ciliated rosettes " of the seminal ducts are found 

 in the tenth and eleventh rings, and by these the developing sperm- 

 cells of the testes pass into the seminal reservoirs or vesicles, which 

 become gradually larger as sexual maturity apjiroaches. 



After an account of the minute structure of the seminal vesicles, 

 the author passes to his more immediate subject. 



Development of the Spermatozoa. — " If a portion of the contents of 

 a seminal reservoir are examined in salt solution, a great many of the 

 stages of the developing spermatozoon are exhibited in one field." 

 In his account of this subject, the author makes use of some terms 

 suggested to him by Professor Lankester ; the spcrmatospore is a term 

 applied to the " constituent cells of a testicle, derived from tho 

 primitive germ-epithelium " ; these cells, by the division of their 

 nuclei, give rise to " spermatospheres" or " sperm-polyplasts." " Each 

 constituent of a sperm-j^olyj^last is a spermatoblast, and when the 

 process of division is over each spermatoblast becomes a sperma- 

 tozoon. It does not, however, hai:)pen that the whole spermatosjihere 

 is converted into spermatoblasts ; there remains a passive portion, 

 which in the earthworm occupies a central position ; this is tho 

 " sperm-blastophore," or " blastophoral cell." 



The author then enters into a careful account of the development 

 of the bodies thus defined, which is illustrated by his own drawings, 

 and comes to conclusions which are best stated in his own succinct 

 resume : The nucleus of the spermatospore in the young testis is of 

 unusually large relative size ; the second nuclei to which it gives rise 

 stand out around tho central mass (blastojihore) of tho generating 

 spheroid with very little protoplasm clothing them. The nucleus 

 undouhtedhj becomes the rod-like head of the earthivorm's sperma- 

 tozoon, and tho filament is as undeniably formed from non-nuclear 

 protoplasm. 



The sperm-blastoplioro of tho earthworm is, however, non- 

 nucleated, while in the frog and salamander the corresponding boily 

 is nucleated. This diflfercnce is, it is suggested, duo to the fact that in 

 the earthworm the spermatoblasts are further developed, not in testes, 

 but in the seminal reservoirs, while in tho vertebrates just mentioned 

 a portion of the blastophoro alone passes oil', while the rest remains 

 ready to resume its activity. In fact, what hai)pcns in the eartli- 

 worm is the remarkable i)henomcnon of tho primitive testis-cells 

 passing into another organ in order to xmdorgo their development. 



Embryology of Ligula.* — M. Moniez, in correcting and adding 

 to tlio recent accounts of this phenomenon given by MM. Duchanip 

 and JJunnadieu, points out that before develo])ment conunenccs tho 

 egg consists of a single egg-ccU (which has been taken for a germinal 

 vcsiclo) ; this lies in tho midst of nutritive globules of various sizes, 



* ' l?iill. Sci. IKp. N.ird,' iii. (ISSQ) p. 112. 



