XXX RHIZOPHORA 457 



siderably longer than for R. mangle, which is sufficiently indicated 

 by the difference in the average length of their hypocotyls on the 

 tree in Fiji, that for R. mucronata being sixteen inches, and that 

 for R. mangle nine or ten inches. 



The only other observations that have come under my notice 

 relating to this subject are those made by Jacquin on Rhizophora 

 mangle in the West Indies in the middle of the eighteenth century. 

 The results are literally quoted by Warming ; but I have referred 

 to the original account in the work of Jacquin, entitled Selectarum 

 Stirpium Americananim Historia, Vindobonse, 1763. According 

 to this observer the seedling falls from the tree in the twelfth month 

 from the fecundation of the flower. This happened in my obser- 

 vations on the same species in Fiji in the eighth or ninth month, 

 Jacquin states that the tip of the radicle protrudes from the fruit in 

 the third month, whilst my results give it as taking place in the 

 fourth month. The difference in the length of the total period, it 

 may be remarked, would be to a great extent determined by the 

 varying length acquired by the seedling before it drops from the 

 tree. In ordinary conditions it averages about ten or eleven inches, 

 and the hypocotyl itself attains a length of nine or ten inches on 

 the tree, both in Fiji and Ecuador ; but in sheltered localities it 

 may attain a length half as long again. I have already pointed out 

 in the case of the fruits of Rhizophora mucronata that a year and 

 more would be sometimes required, and the same remark would 

 apply to unusually long fruits of R. mangle. Local conditions 

 would often produce varying results, both in the rate of growth of 

 the hanging seedling and in the duration of the period of its attach- 

 ment to the tree ; but it is probable that nine or ten months would 

 represent for the genus the average length of the period between 

 fertilisation of the ovule and the detachment of the seedling from 

 the parent tree. 



The mode of separation of the seedlings of Rhizophora mangle and 



Rhiaophora mucronata 



This is a process of expulsion almost akin to parturition, and is 

 brought about by the outward growth of the neck of the cotyle- 

 donary body. There is much that is of great interest in this subject ; 

 and I may add that Haberlandt, in a memoir published in the 

 Annales du far din Botanique de Biiitenzorg for 1894, gives the 

 results of an elaborate study of the viviparous process in this and 

 other genera of mangroves. The same analogy seems also to have 



