THE MANGROVE OF THE BOMBAY PRESIDENCY. 649 



this : As the protruding thick radicle grows on the tree to a finger's 

 length only, it happens very often that it does not fall perpendicularly 

 and thus fastens itself only insufficiently or not at all to the muddy sub- 

 stratum. Instead of it several of the numerous and. pointed calyx-lobes 

 hide themselves in the mud, and, as they are somewhat curved, fasten 

 sufficiently, the embryo lying horizontally on the ground till the first 

 root is so far developed as to give the plant the necessary resisting 

 power. The secondary roots of the Bruguieras are not completely buried 

 in the mud, for after a short or more less horizontal growth, they 

 ascend in an oblique direction to the surface and beyond it, descend 

 again and, disappearing in the soil, leave a knee-like portion ex- 

 posed to the air (Fig. 3, Plate A.) In Bruguiera gymnorhiza, especially 

 the roots grow luxuriously in thickness and height, so as to form round 

 the stem a most curious net-work of brown branches. If we examine 

 under the microscope a transverse section of such a root-piece of Brug- 

 uiera gymnorhiza, the anatomical structure of the periderm shows very 

 large lenticels. As these are organs which correspond to the stomita of 

 the epidermis and serve to admit oxygen to the living internal tissues, 

 we mast consider those roots as a special respiratory system. It is 

 obvious that the muddy substratum is not permeated by too great a 

 quantity of oxygm, we may even say there is a lack of it. It is just 

 for want of this necessary element that the plant was obliged to produce 

 special adaptations to its surroundings, and it did so in a very ingenious 

 and simple way. In Bruguiera can/opJiylloides the usefulness of 

 that contrivance is partially frustrated by the circumstance that the 

 periderm of its roots is gradually cast off. It would be an interesting 

 object of stuly to investigate the reasons thereof and to find out what 

 the effects are in consequence of it, or whether, perhaps, there arise new 

 adaptations in other parts of the plant. 



In the tidal swamps along the coast there are two further species of 

 Rhizophoraceae : Ceriops candolleana, Arn. and Kandelia rheedii, 

 W. et A. 



The former is a glabrous shrub or small tree, reaching a height of 

 3 to 6 ft. The opposite, entire leaves are coriaceous and glabrous. The 

 petioles are rugose and glabrous. The calyx-lobes are coriaceous. 

 The white glabrous petals are furnished at the apex with 3 short, clavate 

 bristles. The slightly conical, coriaceous fruit is ^ to f in. long. The 

 deeply grooved and angled radicle, reaching sometimes 1 ft. before 



