1854.] Linnean Society. 331 



those situated higher up in the stomach ; they are softer also, and 

 their outward filaments (or membranes) are thinner and more porous, 

 and thus they are fitter for impregnation — for absorbing the milt of 

 the male as it is poured over them." And again, p. 185, "Although 

 the unripe ova should be expressed, they w^ould be useless for pro- 

 duction, for their absorbing pores are still closed against the inter- 

 penetration of the milt, and consequently in this state impregnation 

 is impossible." In like manner Mr. Jacobs, in a communication 

 published in the 'Hanover Magazine' for the year 1763, quoted in 

 Yarrell's ' British Fishes ' (ed. 2nd, vol. ii. p. 93), says of the common 

 Trout and of the Salmon also, " After an egg has been fructuated by 

 the sperma of the male, w^hich slips through an invisible opening 

 into it, it lodges in the white liquor, under the shell and round the 

 yolk." Recent discoveries, Mr. Hogg continues, have shown that 

 the fecundating principle of the male fish (as of every animal in 

 which there is a sexual communion) is solely derived from the 

 seminal animalcules or spermatozoa. In the words of our late 

 distinguished Fellow, Mr. Newport, " The spermatozoa alone, in all 

 cases of communion of the sexes, are the sole agents in impregnating 

 the ovum, and impregnation cannot be effected by the liquor seminis " 

 (Phil. Trans. 1851, p. 172). Dr. Martin Barry indeed has asserted 

 (Phil. Trans. 1840, p. 533, and pis. 22 & 23. figs. 164-169) that 

 he had observed an attenuation, or an orifice like a cleft, in the thick 

 transparent membrane of the ovum of the Rabbit, at the period of, 

 and after, fecundation, through which the spermatozoa enter ; and 

 in a recent communication to the Royal Society (Proceedings, vol. vi. 

 p. 335), the same author has referred to a lately jmblished work by 

 Dr. Keber, in which Dr. Barry states, " That physiologist describes 

 the penetration of the spermatozoa into the interior of the ovum, in 

 Unio and Anodonta, through an aperture formed by dehiscence of its 

 coats, analogous to the micropyle in plants." On submitting por- 

 tions of the external membrane of both the unimpregnated and im- 

 pregnated ova of the Salmon contained in the two phials presented 

 to the Society, to the Society's microscope, Mr. Hogg was unable 

 to detect any perceptible difference between them, even when mag- 

 nified at a considerable power. The membrane in both conditions 

 was a perfectly transparent tissue, and appeared, to Mr. Kippist as 

 well as to himself, to be entirely plain ; that is to say, unfurnished 

 in both conditions with either cells or pores, or anything resembling 

 a cleft or aperture. Examination of the entire ova from both phials 

 with a good lens gave the same result, affording not the least ap- 

 pearance of a cellular or porous structure in their external membranes, 



