20 



THE OPHIOGLOSSALES 



although in the latter a few antheridia are almost always developed before the arche- 



ponia appear. . . , . , ,, 



In the male prothallium the basal "vegetative portion is relatively small 



and often is irregularly lobed, these lobes 

 being not of the nature of true branches, 

 but merely the result of unequal growth. 

 The female gametophyte (fig. lo) has the 

 basal region relatively larger and is even 

 more irregular in form than the male, 

 while the fertile region is shorter and 

 wider. Some of the more elongated types 

 of the male gametophyte are quite similar 

 to the simple prothallium of Ophioglossum 

 moluccanum. As in the other genera, the 

 endophytic fungus is always present and 

 occupies much the same position as in 

 Botr\chium. 



Lang found that the growth is due 

 to the activity of a single apical cell having 

 the form of a four-sided pyramid, much 

 like that found in Ophioglossum pendulum. 

 The lateral segments divide by periclinal 

 walls, and from the superficial cells thus 

 formed originates the layer of tissue from 

 which the sexual organs arise. The inner 

 cells contribute to the axial tissue of the 

 gametophyte. The antheridia in the male 

 plants are evenly distributed about the 

 periphery, so that in cross-section they form 

 a nearly uniform circle. The axial tissue, 

 especially in the male prothallium, has the 

 cells much elongated, and Lang thinks 

 they are useful in the conduction of plastic material from the basal region of the 

 prothallium to the growing point. 



The outer part of the basal region consists of two or three layers of somewhat 

 flattened cells, which, like the corresponding tissue in Botrychium, are free from the 

 endophyte. From some of these superficial cells there are developed unicellular, 

 elongated rhizoids, with markedly cutinized walls. This cutinization extends to 

 the outer walls of the superficial cells, while the inner walls of these cells, as well as 

 those of the inner tissue, show the cellulose reaction. The formation of the lobes 

 of the basal region are due, not to definite apical growth, but to irregular cell divi- 

 sions in the outer layers, which remain free from the fungus which occupies the 

 greater part of the central region of the lobes, as well as the axis of the main shoot 

 of the prothallium. 



The central tissue is made up of about equal parts of infected and uninfected 

 cells. The latter, as in the other cases investigated, contain starch granules which 

 are absent from the cells harboring the fungus. Fungus hyphae were seen in many 

 cases to penetrate the rhizoids, but it is highly probable that in H elminthostachys 

 also there is a primary infection at an early stage in the germination of the spores. 



Lang notes that in the older male prothallia the fungus is dead and the further 

 growth of the prothallium is dependent upon the amount of reserve food (mainly 



Fig. io. 



A. Gametophyte (pr) of Helminthostachys zeylanka, with 



young sporophyte attached; v, primary root. X 4. 



B. An older sporophyte, with fully-developed second leaf. 



X2. CQtj rudimentary cotyledon. 



C. Young second leaf, showing venation. X5. 



