STRUCTURE.] STOMATES OF MYZODENDRON, 141 



heat. On bringing this fissure within the focus, it is seen to 

 be replaced by one having its longer axis in the opposite 

 direction, which is derived from the oval figure of the 

 apparatus at its base. Among the fragments may be seen 

 numerous separated specimens of the stomatic apparatus. 

 This is described by Dr. Bird, as oval in outline, nearly flat, 

 and measuring ^i its long diameter ir i-^ of an inch. It 

 consists of a frame of silex formed of two pieces, thick at 

 their convexities, thin at their concavities, nearly touching 

 above and below, and grasping between them two long and 

 flat structures, fissured (apparently) in a pectinate manner, 

 and tapering from their middle towards either end. In 

 most specimens an opening exists between these structures ; 

 in others they are quite in contact. In some the thinner and 

 laminated portions of the frame are perforated by three well- 

 defined apertures, but this is by no means constant. The 

 apparatus thus consists essentially of four pieces, viz., two 

 curved frames with their laminae and two linear pectinated 

 structures; and these are placed at the base of a conical 

 eminence opening by a transverse fissure. By what means 

 it is retained in its position, Dr. Bird has not been able 

 satisfactorily to ascertain." 



Another singular kind of stomate has been described 

 by Dr. Joseph Hooker, in the parasite called Myzodendroii 

 punctulatum. He describes them as being placed one on 

 the apex of each tubercle of the stem, and communicating 

 with the cavity or chamber beneath, the respiratory cavity of 

 some authors. " The cells of which the cuticle is composed 

 are so completely incorporated into a uniform integument, 

 that the curved utricles, which bound the mouth of the stoma 

 in most plants, are here hardly apparent, though it is to their 

 presence that the ridge is due. The aperture itself is con- 

 stricted in the middle, somewhat in the form of an hour- 

 glass, but an opening is generally, perhaps always, left 

 between the adjacent edges of this constriction or diaphragm. 

 The stoma thus expands both outwardly and inwardly into a 

 sort of cup, the outer of which is frequently filled with an 

 opaque mass, and the chambers beneath traversed by fila- 

 ments of a viscid substance, stretching from one wall to 

 the other. In the internal cavity, when empty, parallel 



