440 Dr. L. Eadlkofer on Fecundation in the Vegetable Kingdom, 



His observations were confirmed by Meissner*, and then by 

 BischotFt, previously Barry^s opponent. Beyond this, by Nel- 

 son J (and Meissner, loc. cit.) in Ascaris mystaoc, by Newport§ 

 in the ovum of the Frogs ; by Leuckart || and Meissuer (/. c.) 

 in the Insecta ; by the latter, also, in Lumbricus [I. c.) ; and by 

 Lacaze-Duthiers^ in Dentaliinn. 



The modes in which the penetration of the sperniatozoids is 

 rendered possible, are diversified. Either the coat of the ovum 

 (chorion) or vitelline membrane, or both, presents ready-made 

 holes — micropijles — at determinate points, especially in those 

 cases where the whole coat is of tough texture (as in the Insecta, 

 in Gammanis, in the Holothuriad?e, certain Star-fishes, Worms, 

 bivalve Mollusks ; probably also in the Frogs, bony Fishes, &c.) ; 

 or the coat is of such consistence that the sperraatozoids can pene- 

 trate at any point whatever, without the pre-existence of orifices, 

 as in the Mammalia**; in a third case, finally, the coat is en- 

 tirely wanting at the time of fecundation, the ovum consisting 

 then solely of a compact mass of yelk, into which directly pene- 

 trate all or part of the sperniatozoids, as in the Earth-wormft. 

 We perceive at once, from the last circumstance, that the mem- 

 brane of the ovum cannot constitute any essential part of the 

 ovum. 



Of the subsequent fate of the spermatozoids which pene- 

 trate the ovum, of the share which they take in the immediately 

 succeeding changes in the ovum, we must own ourselves, in 

 point of fact, ignorant. 



Let us hear Leuckart on this point |J : "The only thing that 

 we know definitely is this : that the spermatozoids, which partly 

 ])enetrate into the vitellus, partly remain in the immediate vici- 

 nity of the vitellus, between this and the vitelline membrane, 

 are gradually dissolved (according to my observations on Melo- 

 phagus and Ephemera) far more rapidly than spermatozoids which 



remain outside What, however., becomes of the remains of 



these fecundating elements, is at present unknown to us 



* G. Meissner, Beobacht. ub. das Eindring. der Samenelemente in den 

 Dotter. Siebold u. Kolliker's Zeitschr. fiir wiss. Zoologie. Bd. vi. Heft ii. 

 (1854). 



f Bestatigung der von Dr. Newport bei den Batrachien u. Dr. Ban-y bei 

 den Kaninchen behaupt. Eindring. &c. 1854. 



X II. Nelson, Reproduction of Ascaris mystax. Phil. Trans. London, 

 vol. 142. p. 563, 1852. 



§ G. Newport, Ou the Impregnation of the Ovum in the Amphibia. 

 Phil. Trans. Loudon, vol. 143. p. 233, 1853. 



ll Miiller's Arc!)iv, 1855, p. I'O et seq. 



^ Vide Leuckart, op. cit. p. 249. 



** Leuckart, /. c. ft Meissner, /. c. 



XX Op. cit. p. 252. 



