XXX BRUGUIERA 465 



fruit on the inclosed plumular end of the seedling becomes slacker, 

 the union with the cotyledons becomes weaker, and the connection 

 of the fruit with its peduncle at the basal joint becomes slighter. 

 Usually the fruit falls before the seedling is ready to drop out, and 

 the connection is sevei'ed after a few days' flotation in the water ; 

 but sometimes the union between the seedling and fruit is weaker 

 than that between the fruit and its peduncle, and in that case the 

 seedling falls and leaves the fruit containing the cotyledons on the 

 tree. The whole process of separation is much simpler than with 

 species of Rhizophora. Here it is mainly a matter of the failure 

 of the nutritive supply, whilst with Rhizophora it is almost a 

 process of parturition. 



Haberlandt, in the memoir before quoted, describes quite a 

 different mode of detachment in the case of Bruguiera eriopetala. 

 Here the seedling falls normally whilst still attached to the fruit, 

 and the separation is subsequently effected by the expansion of the 

 mouth of the calyx-tube due to the swelling of the " endosperm- 

 neck " from the entrance of water. 



Summary 



(i) There are four typical mangroves of the Rhizophoraceae in 

 Fiji, Bruguiera rheedii, Rhizophora mucronata (the Asiatic 

 species), Rhizophora mangle (the American species), and the 

 Selala, a seedless form intermediate between the two species of 

 Rhizophora just named, but nearest to the Asiatic species. 



(2) It is shown that the sterility of the Selala is connected with 

 the impotent character of the pollen ; and since the ovules appear 

 capable of fertilisation this is held to indicate that cross 

 fertilisation has not been in operation in producing the barren 

 form. 



(3) Good reasons are given for the belief that the Asiatic 

 species of Rhizophora is the parent of the Selala, not as the result 

 of a cross between the Asiatic and American species, but as 

 connected with dimorphism, the Asiatic species producing two 

 kinds of offspring, one of them with impotent pollen. 



(4) In support of this view it is pointed out that there are two 

 forms of Rhizophora mangle in Ecuador, one of which comes near 

 the Fijian Selala, though producing seed. There could thus be no 

 question of crossing, since but one species occurs there. 



(5) The Selala reproduces itself in a vegetative fashion when 

 growing, as it often does, in an inclined position. The parent 



VOL. II II H 



