PTERIDOPHYTA 



305 



Sexual Organs. The gametophyte is usually monoecious. The antheridium 

 closely resembles in its structure and development that of Equisetum or the 

 eusporangiate Ferns. The spermatozoids, however, are much smaller, and are 

 biciliate like those of the Bryophytes. This fact, together with the structure of 

 the archegonium, indicates a nearer resemblance to the Bryophytes than is found 

 among the other Pteridophytes. The archegonium usually has a large number 

 of neck canal-cells, instead of the two found in most of the other Pteridophytes, 

 and the neck in cross-section sometimes shows five to six rows of outer neck- 

 cells. 



Par 



FIG. 271. A-D, Lycopodium cernuum. A-C, young gametophytes. D, an older one, 

 Pr, with sporophyte attached (X 12) ; PC, protocorm; R, root. E-H, L. phleg- 

 maria. E, F, antheridia. G, spermatozoid. H, archegonium. (After TREUB.) 



Bruchmann (13), who has made the most recent study of the 

 gametophyte in Lycopodium, recognizes five types of gametophyte, 

 all except one being subterranean, but in some cases developing 

 chlorophyll if exposed to the light. The upright cylindrical body, 

 with its crown of leaflike lobes, he compares to the radially sym- 

 metrical gametophyte of the Mosses, and he seems inclined to connect 

 Lycopodium with these rather than with the Hepaticse. The great 

 differences in the character of the gametophyte should be sufficient 

 ground for a separation of the genus into at least five. 



The Embryo 



The embryo (Fig. 272) of Lycopodium differs from that of all other Pteri- 

 dophytes except Selaginella, in having only a part of the embryo devoted to the 

 formation of the sporophyte. The first division in the young embryo, which 



