SELAGINELLA GAMETOPHYTE 273 



by the potash, that a part of the contents of the spore is 

 traversed by a distinct network of cell- walls, forming 

 a meniscus-shaped mass of tissue. If plenty of spores 

 are to be had, it will be found better to embed a 

 quantity of them, and to cut sections, mounting them 

 in glycerine. Observe 



1. The character of the wall, consisting of 



a. An outer thick, yellow exospore. 



1. An inner thin endospore. 



2. The contents as above described : the natural 

 position of the cellular tissue of the prothallium may 

 be seen to be at the apex of the cavity of the spore. 



For the more accurate study of the contents of the macrospore, 

 serial sections should be cut with the microtome, stained, and 

 mounted in canada balsam : it is by this means that the details 

 of the prothallus can be observed with greater ease and certainty. 



XII. Spores of both kinds should be collected in 

 considerable quantity by drying on paper, and then be 

 sown on moist soil or sand, and left to germinate. In 

 a few weeks young seedlings will be seen with an erect 

 axis, bearing small leaves. Note that the axis of the 

 seedling branches at an early period. 



Remove some of these seedlings from the soil, and 

 note the monopodial branching of the root, and the 

 macrospore still attached laterally to the axis. 



Longitudinal sections should be made through the 

 young seedling, so as to traverse also the macrospore 

 'attached to it : in such sections it will be readily seen 

 that a lateral outgrowth (the foot) projects from the 

 base of the axis into the cavity of the macrospore : also 

 that the latter is filled with a cellular tissue of the 



