6 J. BURTON ON THE REPRODUCTION OF MOSSES AND FERNS. 



on the thick cushion of the prothallus, among the rhizoids. They 

 have a neck projecting beyond the surface, reminding us of the 

 similar organs among the mosses : but there is no swollen lower 

 part, as in the former case; the body or " venter," as it is called, 

 is formed of the neighbouring cells of the prothallus itself. The 

 oosphere or germ -cell lies in the venter, and a line of cells in the 

 neck, on the maturity of the organ, becomes gelatinous, and 

 forces open the neck, some of it emerging. Into this the sperma- 

 tozoids swarm, and, attracted by the presence of malic acid, proceed 

 down the canal. Finally one reaches and combines with the 

 germ-cell, and thus fertilisation is brought about. The germ- 

 cell, now the embryo, undergoes cell-division and develops into a 

 young fern, it being nourished by the prothallus until leaves are 

 formed. Thus we return to the fern plant bearing non-sexual 

 spores, from which we started. 



From this description it is at once obvious that the fern plant 

 itself does not correspond in the life-cycle with the moss plant, 

 but with the capsule of the moss, as they alike produce non-sexual 

 spores, and each of them is the sporophyte portion of the cycle. 

 It follows that the inconspicuous prothallus of the fern is repre- 

 sented by the leafy stem of the moss, as they alike bear the 

 antheridia and archegonia, and are the oophytes in the cycle. 

 This is a most important distinction, for although the Bryophyta 

 and Yascular Cryptogams are by some united as the Arche- 

 goniateae, because of the similarity of the female organs in the 

 two groups, yet it is between them that the parting of the ways 

 occurs. In the ferns and all above them the sporophyte is the 

 manifest plant ; while below the ferns, beginning with the mosses, 

 it is the member of the life-cycle which bears the sexual organs — 

 in short, the oophyte — which is the more conspicuous, and the 

 spore-bearing portion is usually looked upon merely as the fruit, 

 though really another generation. 



It will, perhaps, be a surprise to some to learn that in ordinary 

 flowering plants — technically the Angiosperms— it is the sporo- 

 phyte which is the visible and commonl}< known portion of the 

 life-cycle ; or, indeed, that any alternation of generations can be 

 recognised in the sense in which I have used the expression. Yet 

 such is the fact. The matter is much too lengthy and intricate to 

 be effectually treated here ; but although we can all see and are 

 acquainted with the sexual reproduction in these higher forms, 

 it must be remembered that underlying it, although much modi- 

 fied, and unintelligible except when compared step by step with 



