184 Mr. W. H. Benson on new species of Cyclostoma. the first steps in the formation of an embryo." These con-siderations become analogically of importance in leading ns to the discovery of the real history of the Olacacea. Something in relation to this subject might be learned, if we could better understand the origin and development cf the embryo under ordinary circumstances, for the facts are still undetermined that can prove which of the two theories of the nature of vegetable reproduction is founded on truth ; the one maintaining that the pollen-grain penetrates the embryo-sac, and hence comes into immediate contact with the body of the nucleary vesicle, in order to effect its fertilization ; the other denying this assertion, and declaring that it does not penetrate the sac, but merely discharges its function of impregnation, by external impression. Similar theories have long been disputed among zoologists, some con-tending that the spermatozoon does not penetrate the ovum in order to effect its impregnation, as mere external impact is suf-ficient to accomplish this function, while others declare the necessity of immediate contact, and that in proof of this they have seen the spermatozoa within the shell of the ovum. This point has just been determined by Mr. Newport, in a very in-teresting paper read before the Linnsean Society, in which he proves satisfactorily that the former view is conformable to truth. He has ascertained the important facts, that the presence of active spermatozoa are absolutely necessary to impregnate the ovum ; that this is effected by simple impact ; he has noted the time necessary to complete the operation, and has observed the internal change that immediately takes place in the body of the nucleus ; and moreover he has found that the spermatozoa, after producing this effect by simple external impact, become inert and lose all power of motion. Mr. Newport has suggested that these circumstances, by analogy, may assist in determining the theories in dispute among vegetable physiologists ; and he has pointed to the curious fact recorded by Mr. Griffith (Linn. Trans, vol. xx. p. 393) of the irritability or oscillatory motion seen within the boyaux of the pollen-grains of Dischidia at the period of impregnation of the ovules, which may perhaps be in some degree analogous to the vivacity of spermatozoa under parallel circum-stances. XVI. — Geographical Notices, and Characters of fourteen neiv spe-cies of Cyclostoma, from the East Indies. By W. H. Benson, The following new species of an interesting genus of operculated Land-snails belong chiefly to the mainland of India, and were collected in the Sikkim Himalaya; among the hills to the north-east of Bengal, and in the Peninsula of Southern India, from the
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