TWO SPECIES OF PODOSTExMON. 



107 



to be supplied by fibres of very small diameter packed very closely 

 together, and, at least after maceration in spirit, filled with grumous 

 matter. These fibres form the veins above described as existing in 

 P. Wallichii, vrhich pass up along the centre of each axis of 

 inflorescence, supplying in their course the scales, the column of sta- 

 mina, and terminating by forming the costae of the ovarium. But in 

 P. Griffithii these fibres are confined entirely to the axes of inflores- 

 cence ; and although a branch appears to pass up along the staminal 

 column, this appearance would seem to result rather from a discoloration of 

 the tissue than from the presence of distinct fibres. The remainder of the 

 fronds consist of dense cellular tissue, the cells varying considerably in 

 shape and containing, particularly in P. Griffithii, much granidar amy- 

 laceous ? matter. No stomata exist, although the distinctness of the cutis 

 in the last mentioned species would lead one to suspect their existence. 

 The spathae appear to be the only entirely cellular parts. The roots of 

 P. Wallichii consist, like the peduncles of both species, of an outer 

 cellular and a central fibrous portion. 



In P. Griffithii each axis of inflorescence is perfectly distinct ; each 

 arising from the parenchyma, the cells of which are there smaller and all 

 converging towards the peduncle. Opposite to each of these points the 

 fronds adhere so firmly to the bodies on which they grow, that it is almost 

 impossible to detach them to any considerable extent. The adhesion is 

 indeed so extraordinarily firm, that each disc on its detachment tears away 

 with it a corresponding portion of the surface of the rock or stone on which 

 the plant grew. On detaching the axes of inflorescence small round alveoli 

 are left, penetrating or reaching to the disc of adhesion. This is very 

 conspicuous in old plants, which appear like brownish, rather thick, 

 frequently perforated films spread over the surface of the bodies to which 

 they are attached. 



The most remarkable points of structure are perhaps the composition 

 of the pollen, and the deciduousness of the cellular portions of the peduncle 

 and ovaria. 



