CH. V] RUBIACE^E 47 



chiefly on the mode of dehiscence septicidal (Conda- 

 minea, &c.) or loculicidal (Isidorea, Fig. 47, &c.), or by a 

 lid (Pyxis) as in Argostemma, Mitracarpus (Fig. 48), 

 and the infructescences of Opercularia (Fig. 49) and 

 Pomax. Then we have a series where the capsule 

 remains indehiscent (Dentella, &c.). 



A BCD 



Fig. 49. Opercularia aspera. A, pyxis-like infructescence dehiscing. 

 B, operculum of iufructescence bearing several fruits. C, single fruit. 

 D, longitudinal section of single fruit (Bai). 



Now the play sets in in two noteworthy directions : 

 first, in the reduction of the seeds to two or even one, 

 and, second, in the passage of the mesocarp through a 

 leathery consistency to a succulent one. 



In cases where the seeds are reduced to one in each 

 carpel or chamber, we often have the valves separating 

 and each enclosing its seed, to which it forms an invest- 

 ment. These mericarps look like Achenes, but it is 

 customary to call such forms Cocci (Fig. 50). In some 

 e.g. Xanthophytum, Diodia, &c. we have the closed 

 mericarps simply falling away, and very like achenes ; in 

 others e.g. Cremocarpus the two mericarps remain 

 attached for a time to the carpophore, as in the fruit 

 (Cremocarp) of an umbellifer. In Adina, &c. the cocci 

 split after separating, whereas in Galium (Figs. 51, 52), 



