156 Miscellaneous. 



sperm atozoids whicli are only a few seconds later than the first 

 one. The penetration takes place at any point of the surface of the 

 vitellus. I am of opinion that the normal fecundation of the starfish 

 is effected by means of a single spermatozoid to each ovum ; in the 

 sea-nrchin this fact is perfectly evident. 



The point of penetration becomes the centre of a male star or aster ; 

 in the middle of the aster there is formed an aggregation or male 

 pronucleus, which amalgamates Avith the female pronucleus exactly 

 in the same manner as is observed in the sea-urchin. I need not, 

 therefore, refer to it particularly. 



From what precedes it results that the disappearance of the ger- 

 minal vesicle and spot and the expulsion of the rejected materials 

 are mere phenomena of the maturation of the ovule, and that the 

 female pronucleus has no genetic connexion with the nucleolus of 

 the ovule, and, lastly, that the spermatozoid exerts upon the vitelline 

 material not only an attraction of contact, but even an attraction at 

 a distance. — Comptes liendtts, Feb. 19, 1877, p. 357. 



On the Fecundation of the Egg in the Echinus. 

 By M. J. Pekez. 



Every new tact relating to the fecundation of the egg being of 

 considerable importance, it is essential not to regard it as defini- 

 tively acquired in science until it has been subjected to careful 

 checking. It is for this reason that I thiuk it my dutj' to make 

 known the observations that I have made upon the egg of Echi- 

 nus escidentus, with the purpose of verifying the remarkable facts 

 announced by M. H. Fol, in a note published in the ' Comptes 

 Reudus ' of the 19th February last. 



I have twice had the opportunity of observing, at a point of the 

 surface of the ovum, the projection described by M. Fol, and which 

 that naturalist regards as raised by an attraction at a distance ex- 

 erted by the sperniatozoid nearest the vitelline sphere ; but I found 

 it impossible to ascribe to it the least importance in the act of im- 

 pregnation. In fact, in one of the cases observed by me, no sperma- 

 tozoid was at any moment opposite to this eminence up to the time 

 of its disappearance by the rising of the viteUine membrane. In 

 the second case a spermatozoid immersed in the mucous layer nearly 

 at the middle of its thickness, after remaining motionless for a few 

 seconds, moved briskly down to the apex of the projection. I saw 

 no delicate prolongation of the latter emitted towards the spermato- 

 zoid ; nor (and this is still more important) did I see the spermato- 

 zoid JJoiv, according to M. Fol's expression, into the vitellus. It 

 remained motionless, applied to the surface. Scarcely was it fixed 

 there when another speimatozoid, following the same road as the 

 first one, passed through the thickness of the raucous zone in two or 

 three bounds, and also laid itself upon the surface of the little eleva- 

 tion. Two more spermatozoids took the same course, but stopped 



