184 



Dansk Botanisk Arkiv, Bd. 3. Nr. 1. 



my plant has just a fairly regularly dichotomous ramification, 

 and the angle between the branches is often obtuse. 



Judging from Yendo's figure (1. c, pi. IV, fig. 4) the Japanese 

 plant seems also to be more irregularly ramified and to form 

 more compact tufts than the West Indian one. 



As to the anatomy I found it agreing very well with M™^ 

 Weber's excellent description. In the joints the central strand 

 consists of two rows of long cells, alternating regularly with one 

 row of short cells. The long cells have a length 

 of about 100//, the short ones of about 20 // only. 

 The cortical tissue consists of several layers of 

 short cells, shortest at the periphery. In the young 

 thallus the cortex consists only of a few layers of 

 cells, in the older one, on the other hand, of 

 several, because the cortical layer increases, as the 

 plant grows older, in thickness (comp. Solms- 

 Laubach, 1. c). 



As mentioned by this investigator and described 

 more particularly by M™^ Weber the nodes of 

 Amphiroa rigida consist of two rows of cells (Fig. 

 173). The cells in these rows are of nearly the 

 same size and have thick walls, except in the upper 

 and lower ends where they meet the cells of the 

 central strand. Here the transverse walls are 

 horizontally placed while the cells in the middle of 

 the node meet each other with oblique walls, being 

 in this way more firmly connected. As suggested 

 by M™*^ Weber this might, perhaps, help to increase 

 the strength of the node. A good illustration of 

 the node is given by Yendo in "Corallinæ veræ 

 Japonicæ", pi. 1, figs. 5 — 6. 



To judge from Harvey's description of Am- 

 phiroa fragilissima in Nereis, part II, p. 85 the 

 plant he has had before him seems to be the same as the present 

 one. Harvey's description seems in any case quite to agree 

 with my plant; but, in order to settle exactly their identity, an 

 examination of Harvey's plant is of course necessary. Harvey's 

 closing remark that it is "an exceedingly fragile species, of which 

 it is almost impossible to preserve more than broken fragments" 

 is also quite in accordance with my plant, this being too very 

 fragile. Most probably this quality has induced Harvey to refer 

 his plant to Amph. fragilissima having not noticed the most 



Fig. 173. Am- 

 phiroa rigida 



Lamx. var. 

 Ant Ulan a no v. 

 var. Part of 

 the node show- 

 ing the acute 



ends of the 



cells. (About 



270:1). 



