984 



DR THOMAS R. FRASER ON STROPHANTHUS HISPIDUS. 



layers of the pericarp become apparent, and it is seen how great is the thickness of the 

 mesocarp relatively to the other layers. When the follicle is mature and dry, the pericarp 

 becomes much thinner, the reduction in thickness being mainly caused by shrinking of 

 the mesocarp. This is rendered apparent when the above illustrations are compared 

 with figs. 3, 4, 5, and 6 in Plate VII., and also by the measurements given below of the 

 transverse section of the pericarp and its layers in a mature and in an immature follicle : — 



Epicarp, 



Mesocarp, 



Endocarp, 



Immature Undried Follicle. 



0-0097 inch. 

 02559 „ 

 0-0078 „ 



02734 



0-00025 metre. 



0-0065 



00002 



0-00695 



Epicarp, 



Mesocarp, 



Endocarp, 



Mature Dry Follicle. 



01 inch. 

 005 „ 



001 „ 



0-00025 metre. 

 00013 

 0-00025 „ 



0-07 



0-0018 



The mesocarp contains numerous vascular fibres arranged in isolated bundles (see Plate 

 V. figs. 5 and 56). The structure of the endocarp is illustrated in Plate V. figs. 5, 5c, and 

 5c?, and the explanation of its hardness is seen in the elongated indurated cells of which 

 it is composed. The circumferential direction of the cells in the inner of its two layers 

 (next the cavity of the follicle) and the longitudinal direction of those in its outer layer 

 (next the mesocarp) is also shown in these illustrations. 



Contents of the Follicles. — When the interior of a mature follicle is examined, it is 

 found to contain three different structures, namely, (a) the placenta, (b) the seeds 

 with their attached comose appendages, and (c) a quantity of fine downy hairs, for the 

 most part loose in the interior. 



(a) The placenta is attached to the inverted carpellary margins, which project into 

 the interior of the follicle in its immature condition, and which, as maturity advances, 

 become split into the two plates that together form the placental or ventral surface of 

 the follicle. The placenta also subdivides into two portions, each of which curves round 

 into one of the lateral halves of the interior of the follicle. In a transverse section of 

 the follicle, each lateral half of the interior is, therefore, seen to be occupied by a curved, 

 almost completely spiral placental membrane (Plates IV. fig. 5 ; V. fig. 5 ; and VII. figs. 

 3, 4, 5, and 6). In the dry follicle, the concave surface of the curved portion of the 

 placenta is smooth, shining, and, like the interior surface of the endocarp, of a pale lemon 

 colour ; and the convex surface is of much the same grey colour as the nearly flat or 

 concave exterior ventral surface of the follicle, with which surface, indeed, it is continuous. 

 This curved portion of the placenta is marked by a number of depressions or pittings, 

 caused by the pressure of the seeds in contact with it. 



