86 JOURNAL, BOMBAY NATURAL HISTORY SOCIETY, Vol. XVII. 



The so-called " pectinate organs " arise as cylindrical bodies from 

 below the scaly stipules and on the sides of the floating leaves. (Fig. 1.) 

 They grow to the length of | — 1 in. without showing any external 

 differentiation ; but, then, there appear round the lower half of the 

 cylindrical axis small globular protuberances, apparently without any 

 regular distribution. Growing in acropetal succession these globular 

 bodies assume an elongated shape, but still remain comparatively 

 stout. When the main axis has reached its full length, i.e. 2 — %\ 

 in., and the lateral structures have attained \ in., the most regular 

 arrangement of the latter can be detected very easily, and even 

 batter than after their full development. The lateral processes are 

 arranged in four spiral rows, all turned to the right. Fig. 2 gives 

 the successive stages of development, and Fig. 3 a diagrammatic 

 view of the arrangement of the lateral cylindrical bodies on the main 

 axis. As soon as the aerial leaves have fallen off, a rapid growth of the 

 lateral structures begins till they attain capillary thinness. Their 

 bases are now reduced in diameter compared with the same in their 

 immature state. Their shape is not quite cylindrical, but slightly 

 flattened, whereas the main axis is cylindrical. In this state of deve- 

 lopment it is extremely difficult to make out the arrangement of the 

 lateral members. I was not able to trace their angular divergence 

 and it seems to me that they are scattered irregularly on the spiral lines. 

 It cannot, therefore, be said, that those organs are pectinate, or 

 pinnatisected, or pinnatipartite, as the lateral processes are distinctly 

 arranged in four spiral rows; and even with the leaves of Myriophyllum 

 they may be compared only so far as also in this water-plant simi- 

 lar capillary processes occur, though in a less perfect form. If the 

 lateral members were arranged in two parallel opposite rows only, no 

 objection could be raised against calling them pectinate, and even if 

 they were located in two spiral rows, the difficulty could perhaps be 

 overcome by explaining the spiral arrangement as effected by the 

 torsion of the main axis ; but as there are four distinct spirals, the best 

 term applicable seems to be Roxburgh's " ramous ", if we do not want 

 to introduce an entirely new name for this special arrangement, which, 

 s far as I know, has not been observed in any other phanerogamic plant. 

 The internal morphology exhibits, likewise, some peculiar features. 

 Only one vascular bundle, situated in the centre, extends through the 

 main axis, and smaller ones through the lateral processes. Eesides, there 



