242 
G. S. West and Olive E. Hood. 
wall is a little variable, but in most cases the central part is shaped 
like a watch-glass with the convex side usually towards the apex of 
the filament. When the cells are swollen they frequently split 
apart by the rapid breaking down of the transverse walls. 
Fig. 1. Ends of two branches of Trentepohlia Montis-Tabula var. ceylanica 
treated with an ammoniacal solution of cupric hydrate. This structure can 
only be seen for a brief period after which the lamellae are gradually dissolved. 
In B the apical cell had been damaged and its functions taken on by the 
penultimate cell, which had already developed an apical cap. A and B, x 500. 
Thus, the statement of Brandt 1 that the transverse walls are 
simple is not true of all the members of this genus. The lamellae 
of the transverse walls, like those of the longitudinal walls, consist 
entirely of cellulose. This is clearly shown by the reactions of the 
cell-walls to reagents and stains. They are soluble in an ammo¬ 
niacal solution of cupric hydrate after first taking on a blue 
colouration, and also soluble in concentrated sulphuric acid. With a 
potash solution they swell considerably. Sulphuric acid and iodine 
solution give a deep blue colouration, and with chlor-zinc-iodine the 
filaments assume a deep violet colour. The walls also stain with 
methylene blue, safranin, rosanilin-violet, eosin and a watery solution 
of fuchsin. 
The apical cell .—Growth in the genus Trentepohlia is entirely 
apical, and the wall of the apical cell in T. Montis-Tabulce var. 
ceylanica consists of successive thin lamellae, which are upwardly 
and outwardly divergent. The lamellae are not entirely continuou s 
round the cell, but each lamella is laid down only within the upper 
half or upper two-thirds of the cylindrical side walls and across the 
apex itself. As the growth of the apical cell continues the last- 
deposited lamella increases in superficial area and gradually bursts 
1 F. Brandt in Beihefte zu Botan. Centralbl. XII., 1902. 
