54 BRITISH ASSOCIATION FOB, THE ADVANCEMENT OE SCIENCE. 



at length at the complicpted machinery exhibited in flowering plants, in which the 

 cell containing the fecundating principle is first matured in the stamen, and after- 

 wards transmitted, through an elaborate apparatus, to the cells of the ovule, which 

 is in like manner enveloped in its matrix, and protected by the series of investing 

 membranes which constitutes the seed-vessel. Thus, as Goethe long ago observed, 

 and as modern physiologists have since shown to be the case, the more imperfect 

 a being is, the more its individual parts resemble each other — the progress of de- 

 velopment, both in the Animal and Vegetable Kingdoms, always proceeding from 

 the like to the unlike, from the general to the particular. But whilst the researches 

 of Brown and others have shown that there is no abrupt line of division in the 

 Vegetable Kingdom, and that one common structure pervades the whole, the later 

 inquiries of Suminski, Hofmeister, Unger, Griffith, and Henfrey, have pointed out 

 several curious and unlooked-for analogies between plants and animals. I may 

 mention, in the first place, as an instance of this analogy between plants and animals, 

 the existence of moving molecules, or phytosperms, in the antheridia of ferns and 

 other Cryptogams, borne out, as it has been in so remarkable a manner, by the almost 

 simultaneous observations of Bischoff and Meissner on the egg, confirmatory of those 

 formerly announced by Barry and Newport, and by the researches of Suminski, 

 Thuret, and Pringsheim, with respect to the ovule of plants. I may refer you also 

 to a paper read at the last Meeting of the Association, by Dr. Cohn, of Breslau, who, 

 in bringing this subject before the Natural History Section, adduced instances of 

 a distinction of sexes which had come under his observation in the lower Algae. In 

 like manner a curious correspondence has been traced between the lower tribes of 

 animals and plants, in the circumstance of both being subject to the law of what is 

 called alternate generation. This consists in a sort of cycle of changes from one 

 kind of being to another, which was first detected in some of the lower tribes of 

 animals; a pair of insects, for example, producing a progeny differing from them- 

 selves in outward appearance and internal structure, and these reproducing their kind 

 without any renewed sexual union, — the progeny in these cases consisting of females 

 only. At length, after a succession of such generations, the offspring reverts to its 

 primaeval type, and pairs of male and female insects, of the original form, are repro- 

 duced, which complete the cycle, by giving rise in their turn to a breed presenting 

 the same characters as those which belong to their own progenitors. An ingenious 

 comparison had been instituted by Owen and others between this alternation of gen- 

 erations in the animal, and the alternate production of leaves and blossoms in the 

 plant ; but the researches to which I especially allude have rendered this no longer 

 a matter of mere speculation or inference, inasmuch as they have shown the same 

 thing to occur in ferns, in lycopodia, in mosses, nay, even in the confervas. "We 

 are indebted to Prof. Henfrey for a valuable contribution to our Transactions in 

 1851 on these subjects, given in the form of a Report on the Higher Cryptogamous 

 Plants; from which it at least appears that the proofs of sexuality in the Crypto- 

 gamia rank in the same scale, as to completeness, as those regarding flowering plants 

 did before the access of the pollen tubes to the ovule had been demonstrated. In- 

 deed, if the observations of Pringsheim with reFpect to certain of the Algse are to 

 be relied upon, the analogy between the productive process in plants and animals is 

 even more clearly made out in these lower tribes than it is in those of higher organ, 

 ization. It also appears that the production in ferns and other Acrogens of what 

 has been callled a pro-embryo ; the evolution of antheridia and archegonia, or of 

 male and female organs, from the former; and the generation from the archegonia 



