Apical Growth in the Genas Trentepohlia. 245 
Bismarck brown, and fuchsin, and one must therefore conclude that 
the caps consist entirely of pectose. 
Brandt 1 has stated that the apical caps which are so frequently 
developed at the extremity of a branch consist of cellulose, and that 
they are the remains of dead, terminal zoogonidangia. As regards 
the species under examination, both of these statements are 
erroneous. In the first place, the caps do not consist of cellulose, 
and secondly, they are without doubt secreted by the apical cell, 
and at no time have any connection with dead zoogonidangia. We 
invariably find in the case of an empty terminal zoogonidangium 
that the supporting cell takes on the function of an apical cell, and 
far from carrying the remains of the zoogonidangium at its extremity 
actually grows through it, leaving it behind as a sort of collar. 
Fig. 5. A, apex of branch (seen in optical section) of T. Montis-Tabulce 
var. ceylanica showing the beginning of new transverse wall (t). B and C, 
showing the completed transverse wall between the apical and penultimate 
cells ; l, a layer of cellulose added after the completion of this wall. A, x 500 ; 
B and C, x 800. 
In the division of the apical cell the transverse wall arises as 
an annular ingrowth from the middle region of the lateral walls 
(Fig. 5 A). The ingrowth in its early stages is at right angles to the 
longitudinal walls, but towards its completion it usually bends 
upwards so that the last-formed part of the transverse wall is convex 
towards the free end of the apical cell. The transverse wall is 
stratified and as the wall is completed the corresponding lamellae 
fuse. 
Soon after the formation of the new transverse wall, another 
layer of cellulose is frequently added within the upper half of the 
penultimate cell (Fig. 5 B and C, l). 
1 Brandt, l.c. 
