XIV L YCOPODINEyE 505 



Liverworts like AntJioceros, and resembles them also in the 

 small biciliate spermatozoids, in which latter respect all the 

 Lycopodineae yet examined agree. This latter point is per- 

 haps the strongest reason for assuming that the Lycopods 

 represent a distinct line of development, derived directly from 

 the Bryophytes, and not immediately related to either of the 

 other series of Pteridophytes. The character of the arche- 

 gonium, as well as the long dependence of the embryo upon 

 the prothallium and the late appearance of the primary root, 

 point to the genus Lycopodiuni as a very primitive type, even 

 more closely related to the Bryophytes than are the eusporangi- 

 ate Ferns. PJiylloglossum, at least so far as the sporophyte is 

 concerned, is the simplest living Pteridophyte ; whether the 

 structure of the gametophyte will bear this out, future investi- 

 gation must determine. 



The close relation of Selaginella to Lycopodmvi is sufficiently 

 obvious. It is, however, interesting to note that Selaginella 

 seems to have retained certain characters that are apparently 

 primitive. These are the presence of a definite apical cell in 

 the stem and root of most species, and the peculiar chloroplasts, 

 which are especially interesting as a possible survival of the 

 type found in so many Confervacese, eg. ColeocJicete, from which 

 it is quite likely that the whole archegoniate series has 

 descended. This form of chloroplast occurs elsewhere among 

 the Archegoniatae only in the Anthoceroteae. 



In the characters of the sporangium and the early develop- 

 ment of the prothallium, Selaginella undoubtedly shows the 

 closest affinity to the Spermaphytes, especially the Gymno- 

 sperms, of any Pteridophyte. The strobiloid arrangement of 

 the sporophylls and the position of the sporangia are directly 

 comparable to the strobilus of the Coniferae. The wall of the 

 sporangium is here not only morphologically, but physiologic- 

 ally comparable to the nucellus of the ovule, and, as there, the 

 macrospore grows, not at the expense of the disorganised 

 sporogenous cells and tapetum alone, but is nourished directly 

 from the sporophyte through the agency of the cells of the 

 sporangium stalk and wall, until the development of the 

 enclosed prothallium is far advanced. The latter, both in its 

 development while still within the sporangium, as well as in 

 all the details of its formation, shows the closest resemblance to 

 the corresponding stages in the Conifers. The formation of a 



