THE GAMETOPHYTE 



17 



germinated in the light. Bruchmann (Bruchmann 2, page 207) also found the 

 earliest stages in B. lunaria, and these corresponded exactly to those in B. vir- 

 ginianum. 



The gametophyte of B. virginianum is a large, tuber-like body, which grows 

 at a depth of about 10 centimeters below the surface of the earth. The smallest 

 of the specimens found by Jeffrey were 2 millimeters in length by 1.5 millimeters 

 in breadth, exceeding in size the fully developed prothallia of B. lunaria. The 

 older ones may reach a length of 20 millimeters. The young prothallia are 

 quite smoothly oval in outline (fig. 6, C), while the older ones are more or less 



Fig. 7. 



A. Young sporophyte of Boirychium virgini- 



anum attached to gametophyte, pr, X2. 



B. A gametophyte with small sporophyte, sp. X4. 



» 



:fi^ 



D 



Fig. 8. — Botrychium lunaria (after Bruchmann). 



A. Two young gametophytes. 



B. An older one, with sporophyte, j/>, attached. 



X16. 



C. Surface view of two antheridia, showing opercu- 



lar cells (shaded). Xioo. 



D. A spermatozoid. X500. 



irregular, and occasionally the anterior end is divided into two equal lobes, 

 probably as a result of dichotomy. As in Ophioglossum, the older parts of the 

 gametophyte are brownish in color, while the young apex appears white. In their 

 earlier stages they are covered with numerous rhizoids, which disappear more or 

 less completely as the prothallium becomes older. The forward end is slightly 

 pointed and there is a definite growing point. The antheridia make their appear- 

 ance first, and together with the archegonia are formed only upon the upper surface 

 of the dorsiventral thallus, which is noticeably different in form from the cylindrical 

 radially constructed prothallium of Ophioglossum. 

 2 



