558 TRANSACTIONS AND PEOCEEDINGS OF THE 



posed of anticlinal filaments, while through its internal 

 cavity there runs a tolerably thin central axis of 

 elongated cells. From each of the component cells 

 of this axis arise (usually at about the middle of 

 the cell at the same or a slightly different level and 

 close together) two branched filaments which pass out 

 either directly or in more or less elongated ascending 

 curves to the small-celled wall of the thallus, the tissue of 

 which they form by their congenital fusion at varying dis- 

 tances from the axis, as well as by their cohesion by means of 

 mucilage (collode) in such a manner that the inner side of 

 the wall is defined with varying degrees of sharpness. The 

 interstitial mucilage (collode) which unites the ramifications 

 of these wall-forming filaments in the formation of the 

 thallus is sometimes terminated abruptly towards the 

 central cavity of the stem, while in other cases it is only 

 indistinctly bounded in that direction and may extend 

 inwards to various distances at different points in the same 

 shoots. Moreover, this mucilage, which shows in the living 

 plant a considerable tenacity, is always very liable to dis- 

 appear after the death of the alga ; it swells up very rapidly 

 in fresh water, and forms a thin gelatinous mucilage, which 

 is made practical use of to a considerable extent in China 

 and Japan. 



In the interior of this more or less hollow thallus are 

 formed rather small-celled thin rhizoids, which vary in 

 number according to the species. They arise from the 

 cells of the branched filaments which go to form the wall, 

 and from their lower and middle cells, i.e., from those 

 which lie next the inner limit of the thallus wall. From 

 these cells the rhizoids, which generally spring from the 

 middle of the cell, grow towards the interior of the thallus 

 and extend to varying lengths within the hollow inner space 

 of the shoot towards the central axis. They are frequently 

 unbranched, though in other cases they are beset with 

 isolated spreading branchlets. 



These rhizoids are very copiously developed in Endo- 

 trichia cervicornis ; in fact, in this species they usually arise 

 from the inner side of the wall in such numbers that they 

 invest the central axis pretty closely, and to a great extent 

 fill up the space here very narrow, between it and the 



