398 SUMMARY OF CURRENT RESEARCHES RELATING TO 



spiral in direction. Hero tho tail of tho spermatozoon is more distinctly 

 than in tho first caso formed at the expense of the protoplasm of tho 

 spermatoblast. The amceboid pscudopodia, which have been described, 

 aro nothing more than the first stage in the elongation of this proto- 

 plasm. 



The differences in tho modes of development depend on the moro 

 precocious fragmentation of tho nucleus in the first case, and there is 

 no morphological value in the difference between these two kinds of 

 spermatozoa. 



Reproductive Organs and Oogenesis of Helix.* — M. Y. Garnault 

 has studied by means of sections the structure of a portion of the repro- 

 ductive organs of Helix aspersa, and also the mode of oogenesis and tho 

 first stages in fertilization. 



(1) In regard to the organs, tho portion known as the " diverticu- 

 lum " or " talon " at tho corner of the albumen gland has been studied. 

 The efferent canal forms, near its posterior extremity, a sort of sac, 

 bordering on the concavity of the albumen gland. This sac is the 

 swollen end of the efferent canal. A little below the point where 

 the swollen portion of the efferent canal is pressed into the albumen 

 gland, it gives origin laterally to a tube, lined by ciliated non-granular 

 epithelium. This tube branches into 3-8 ramifications, ending in culs- 

 de-sac, and lodged between the ascending and the descending or swollen 

 portion of the efferent canal. In the adult these tubes are filled with 

 living spermatozoa. 



(2) In regard to the oogenesis, (a) the follicle is formed from tho cells 

 of the germinal epithelium, becomes delicate in adolescent ova, and is 

 absorbed on dehiscence. (6) The nucleus of the adult ovum has a 

 distinct membrane ; it contains a large deeply stained sphere, and 

 a still more deeply stained corpuscle within the latter. There is 

 a well-developed karyoplasmatic network, with intensely stained cor- 

 puscles at the nodes. The large nucleolus and accessory nucleoli 

 are formed by the concentration of the chromatic material of tho 

 network. 



(3) When the Helix is beginning to deposit ova, the swollen portion 

 of the efferent canal is seen to be full of sperms and ova. Admirable 

 preparations were obtained by 3 per cent, nitric acid and by Delafiold's 

 hsematoxylin. The vitelline expansions discovered by M. Perez were 

 well seen over the whole ovum or at the poles. Their formation is pro- 

 bably due to the irritability of the vitellus evoked by the action of the 

 spermatozoa. 



(4) The author then describes the formation of polar globules, 

 and is convinced that the process has the significance of cellular 

 division. 



(5) The sperms penetrate tho ovum usually by the vitelline expan- 

 sions, which seem to be " cones of attraction." They soon lose their 

 tail and the head increases. Three male pronuclei were sometimes seen 

 in one ovum. The pronuclei increase by the apposition of stainable 

 granules from the vitellus. They soon acquire stellate form, with a 

 central mass and three, increasing to six, lateral masses. The volume 

 increases with the complexity. Never more than one enlarged male 

 pronucleus was seen in the ovum. No male aster was to bo seen. The 



* Coinptes Rendus, cvi. (1888) pp. 675-8. 



