298 



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



central cells are at first formed on the upper, dorsal side of the 

 rhizome, somewhat later on the lower, ventral side and the growth 

 is upon the whole to begin with most vigorous on the upper 

 side. By this habit of growth the summit of the rhizome is tur- 

 ned downwards towards the substratum (Fig. 297), later on by- 

 augmented growth on the lower side this curve is again eliminated. 

 From the pericentral cells of the ventral side of the rhizome 

 hapters grow out, fixing the plant to the ground or to other 

 algæ (Fig. 295). The rhizoids are in open connection with the 

 mother cell; they have very thick walls, their lumen being re- 

 duced to a narrow channel; they end in an irregularly lobed 

 disc. The rhizomes are about 80 — 120 ju thick and the segments 

 about as long as broad or somewhat shorter, about 80« long. 





Fig. 296. Lophosiphonia cristata Fal- 

 kenberg. Transverse section of the 

 thallus. (About 150:1). 



Fig. 297. Lophosiphonia cristata Fal- 

 kenberg. Summit of creeping filament. 

 (About 265:1). 



The erect branchlets are to begin with not curved in their 

 upper end and are destitute of trichoblasts (comp. Fig. 295). But 

 soon the summit becomes curved or even somewhat involute. 

 The hook-formed summit it always turned forwards towards the 

 growth-point of the rhizome. 



When the branchlets have reached a certain length, which 

 varies somewhat in the different branchlets, they begin to develop 

 trichoblasts from the convex side (Fig. 298). The trichoblasts are 

 placed in a single row, at first at some distance from each other, 

 but later on nearer and nearer until at last nearly every seg- 

 ment has a trichoblast. 



The development of the trichoblasts begins very early and 

 proceeds so vigorously that they are rather large even before 

 the segment which bears a trichoblast is divided (Fig. 298). 



The branchlets have at their base nearly the same number 

 of pericentral cells as the rhizome, but higher up, as already 

 mentioned, a larger number. I have counted 10 — 12. At the same 

 time as the number of the cells increases the cells grow shorter; 



