THE GAMETOPHYTE 



21 



Starch) which is left in the cells. It is not clear what role the endophyte plays in 

 the manufacture of the reserve food materials upon which the further growth of the 

 prothalhum depends. It is highly probable, however, that some of the necessary 

 organic elements are derived from the destruction of the fungus tissues which serve 

 as food for the further development of the prothallium. While no data are at hand 

 to prove this, the lack of permanent growing tissue in the prothallium and the com- 

 plete destruction of the fungus make it highly probable that the life of the gameto- 

 phyte in Helminthostachys is restricted to a single season, as it is in Ophioglossum 

 moluccanum. 



Fig. II. 



A. Male gametophyte of Helminthostachys. X8. C. Surface view of ripe antheridium, showing opercular cells 



B. Young antheridium. ^X.^^$. D. An old archegonium. X about 200. 



(Figs. A-C, after Lang.) 



THE ENDOPHYTE. 



The endophytic fungus which inhabits the gametophyte in all of the Ophio- 

 glossaceae is very much alike in all of the species, differing only slightly in size in 

 different forms (fig. 9). A special study was made of this endophyte in Ophio- 

 glossum pendulum, where it is especially well developed. As we have already seen, 

 the endophyte is absent from the younger parts of the prothallium, but in the older 

 parts it is exceedingly conspicuous. Sometimes fragments of a fungus are found 

 outside the prothallium, growing in the humus, and these are evidently the same 

 forms that infect the very young prothallium when it arises from the germinating 

 spores. These external hyphae in some cases have an occasional septum, and this 

 is also the case in those forms which infect the young prothallium. In all of the 

 hyphae seen within the prothallium, however, these septa seem quite absent. The 

 infection of the prothallium through the rhizoids has been noted in all the species, 

 but, as we have already stated, it is probable that the endophyte is derived mainly 

 from the first infection of the very young gametophyte. An examination of the young 

 cells before the entrance of the fungus shows a conspicuous nucleus and numerous 

 starch grains, which stain very strongly with gentian violet. The invading mycelium, 

 whether from the outside of the prothallium or from the adjacent cells, penetrates 

 the cell wall and ramifies within the cell, the growth being entirely intracellular. 

 The hyphae are noticeably thicker than those of the external mycorrhiza. 



The endophyte is perfectly fixed with i per cent chromic acid and it stains 

 well with the double stain of gentian violet and safranine, the walls assuming a 

 violet color and the numerous nuclei staining deep red. In the younger hyphae, 

 which are of varying sizes, the protoplasm is densely granular, but in the older ones 



