THE HIGHER CRYPTOGAMIA. 325 



first frond and the first root as it were with a sheath, are 

 ultimately unable to keep pace with the growth of the 

 latter. These portions are ruptured, and the apices of the 

 frond and of the root become free. Almost at the same 

 time the second frond appears near the place of origin of 

 the first frond, and separated from it by the blunt end of 

 the future principal axis : it has the form of a conical wart 

 (PI. XLIV, fig. 2), which by continual multiplication of the 

 cells of its apex grows rapidly in length. 



As the plant becomes further developed the joints of the 

 stem elongate considerably : the terminal bud remains 

 rather sharply conical. From the underside of the stem, 

 in the immediate neighbourhood of the terminal bud, 

 numerous bicellular hairs enclosing the latter are pro- 

 duced, and further backwards, close underneath the place 

 of origin of each frond, adventitious roots make their 

 appearance. The basal cell of the hairs which are situ- 

 ated on the outer wall of the fruit, divides repeatedly, at 

 a late period and after the complete formation of the 

 apical cell, by transverse septa ; in this respect these hairs 

 bring to mind the scales of the Polypodiacese. 



The large oval ripe spore of Marsilea pubescens, at the 

 time when it is discharged from the ruptured capsule, is of 

 a similar nature to that of Pihdaria globulifera. The 

 inner cavity of the spore is clothed with a very delicate 

 membrane, which becomes somewhat more manifest by 

 distension, upon the application of caustic potash. In 

 contact with this membrane there is found at first a tole- 

 rably thick glassy layer of a yellowish colour. Except 

 at the apex of the spore — the spot, that is to say, which 

 answers to the place of contact of the spore with its 

 three sister -spores produced by the same cell — this 

 glassy membrane is surrounded by an outer membrane, 

 the component parts of which are prism-shaped, and 

 arranged in a radial manner. Out of this outer membrane, 

 and upon the apex of the spore, a portion of the middle 

 membrane protrudes in the form of a blunt wart. The 

 spore is enclosed in a thick layer of clear transparent homo- 

 geneous firm jelly, which extends beyond the apex of the 

 spore almost throughout its entire length. An enlarged 



