FROM MERGUI ARCHIPELAGO. 227 
examination of them did not enable me to detect any stratification; nor did the use of 
the polariscope help me in this respect. After treatment with iodine they show a pale 
violet colour. Granules of precisely similar size and form occur in the rhizoids of a 
specimen of В. longicaulis collected by Mr. Moseley at St. Thomas, which I examined 
among the ‘Challenger’ alge in the British Museum. For what purpose so vast a store 
of reserve material is réquired by the plant can hardly even be guessed at in our present 
ignorance of the biology of these algze. The mass of it is out of all proportion to the 
size of the frond, for example; and though R. longicaulis has a distinct rhizome-like 
branching, which might indicate the direction in which it is employed, nothing of the 
kind is to be seen in А. Andersonii. An examination of these alge in their native seas 
can alone furnish us with an explanation. 
DESCRIPTION OF PLATE XXXI. 
Figs. 1, 2. Rhipilia Andersonii, G. Murr. Nat. size. 
Figs. За, 36, 3c, За, Зе. Frond-filaments. х 1125. 
Figs. 4а, 45, 4c. Rhizoid filaments containing starch. х 117}. 
Fig. 4d. The same. x 450. 
Fig. 5. Starch-granules. . x 900. 
