6 



Veit Beecher Wittrock. 



manner adapted to the absorption of food, nor serves as an affixing 

 organ of the plant. The Pithophoracece, at least those that grow in 

 water, are, as a rule, not attached to other objects, but float free in 

 the water. The terrestrial species, Pithophora Cleveana nob., on the 

 contrary, very often have affixing organs, which serve at the same 

 time the physiological purpose of assimilating organs, *) but these 

 belong to the caulo'id and not to the rhizoid part of the thallus. 



The general, outer shape of the thallus having now been described, 

 a somewhat more extensive account of the nature of its two principal 

 parts, the caul old and the rhizoid, follows next. As I have mentioned 

 above, the caulo'id is, as a rule, ramified. Full-grown individuals with a 

 wholly unbranched cauloid are very rare. Only in two species, P. Cleveana 

 nob. and P. cequalis nob., I have found such specimens twice or trice (pi. l,fig. 

 5). In P. kewensis nob., individuals with very few and small branches (pi. 2, 

 fig. 5) are sometimes found, but I have not seen wholly unbranched specimens 

 of this species. The system of ramification is of different strength in different 

 species. It is feeblest in P. sumatrana (v. Mart.) nob., judging from the 

 rather few and not quite perfect specimens that 1 have had opportunity 

 to examine. All the branches, that exist here, proceed immediately out 

 of the principal filament, and thus all the branches are of the l:st degree. 

 They are usually simple, but not rarely also opposite in pairs. P. kew- 

 ensis nob. and P. Cleveana nob. generally have branches of only one 

 degree (pi. 2, fig. 1, 6, 7, 13), but sometimes those branches ramify, and 

 the branches they develop are then of the 2:d degree (pi. 2, fig. 3). In 

 P. kewensis nob. the branches are always single; in P. Cleveana nob. 

 they are not seldom opposite to each other (pi. 2, fig. 3). P. cequalis 

 nob. has two types of ramification. In one the branches are only of 

 the l:st degree, in the other also of the second. They are always single. 

 In P. polymorpha nob. specimens are found with branches of but one degree, 

 but also with two. The branches of the l:st degree are not seldom placed 

 opposite to each other (pi. 2, fig. 13). P. Zelleri (v. Mart.) nob. always 

 has branches of two degrees, which are partly opposite. In P. Roettleri 

 (Roth) nob. the system of ramification is most powerfully developed. 

 Here branches of three orders are regularly found, of which those that 

 belong to the l:st are placed three in a whorl, but those of the 2:d and 

 3:rd placed singly or in pairs (pi. 2, fig. 18). From this we find, that 



1 ) Regarding these, which are also now and then found in the aquatic species, 

 see pages 10 and 25. 



