188 THE EVOLUTION OF PLANTS 



is altogether that of a seed. In several cases 

 the prothallus has been found well preserved 

 within the megaspore of the "seed," but we do 

 not yet know the structure of the archegonia. 

 The seed-like organ, sporophyll included, was 

 shed as a whole. In some forms it was quite 

 half-an-inch long. 



Essentially, the seed-like characters are the 

 same as in Miadesmia the single megaspore, 

 the seed-coat, and the shedding of the organ as 

 a whole, the megaspore being retained within 

 it. In detail, the resemblance to a seed is some- 

 what less exact in Lepidocarpon the micro- 

 pyle has an unusual form, and the presence of the 

 three abortive spores shows that the Cryptogamic 

 stage had not been left far behind. 



It is quite clear, from many differences in 

 detail between the "seed" of Lepidocarpon and 

 that of Miadesmia, as well as from the charac- 

 ters of the other organs, that the evolution of the 

 two had been quite independent. Clearly, the 

 need for this reproductive advance had made 

 itself felt in two distinct lines of descent in 

 the small herbaceous plants of the same stock 

 with Selaginella, and in the arborescent Club- 

 mosses which constituted the family Lepidoden- 

 dreae. Both these experiments in seed-reproduc- 

 tion seem to have enjoyed a temporary success 

 only there is no evidence that either was per- 



