XIII 



LYCOPODINEM 



487 



thick, and like those of EquiseHmi show a definite two-sided 

 apical cell. This apical growth later disappears and all trace 

 of it is lost in the older lobes. Rhizoids are produced only 

 in small numbers from the cylindrical prothallium body, and 

 are usually entirely absent from the primary tubercle, whose 

 peripheral cells are always occupied by an endophytic fungus 

 which Treub refers probably to the genus Pythiiim. We have 

 seen that similar fungus mycelia occur in the chlorophylless 



Fig. 283. — A, B, very young prothallia of Lycopodium cernuum. A, X250; B, X200. 

 P, Primary tubercle; C, an older prothallium of the same species with the first 

 antheridium ((^), X75; D, a fully-developed prothallium (pr) with the young 

 sporophyte attached, X12; pc, protocorm; R, primary root; E, section through an 

 antheridial branch of the prothallium of L. phlegmaria, showing antheridia 

 {(^) in different stages of development; par, a paraphysis, X180; F, surface view 

 of the top of an antheridium of the same species; o, opercular cell, X180; G, a 

 spermatozoid, X410; H, section of the archegonium of the same species, X 180 

 (all the figures after Treub). 



prothallium of Botrychium, and Goebel found the same in L. 

 inundatum. While in the primary tubercle the fungus occu- 

 pies the lumen of the cells, as it penetrates into the body of the 

 prothallium it confines itself mainly to the intercellular spaces, 

 where its growth causes more or less displacement of the cells. 

 It does not, however, seem to penetrate into the meristematic 

 tissues at the summit. 



The fully-grown prothallium of L. cernuum is a small up- 



