998 PERCY SLADEN TRUST EXPEDITION 
a segment remains undivided : its contents, balled together, look like a large drop of oil 
and have a reddish-brown colour. The first segment succeeding this undivided cell may 
show a division into a central and pericentral cells, the next is undivided, and the 
ultimate one has usually the shape of a spine. Sometimes the top of a branch is 
crowned by a simple or ramified monosiphonous filament. I could find no explanation 
for this difference in development; the monosiphonous filaments are not trichoblasts, 
nor could any trace of these organs be detected. The large undivided cell, with the cells 
above it, falls off after a shorter or longer period, and the branch that carried them is 
blunt in consequence. 
Schematic figure of apex of Amphis- 
betema indica, showing the sym- 
podial growth of main axis and the 
monopodial growth of the displaced 
shoots. After 6 segments shoot I 
is pushed aside by its first branch, 
shoot II is also displaced after 
6 segments by its first branch, and 
the other shoots follow in like 
manner. The displaced shoots 
carry side-branches at every second 
segment. 

The axes have in each segment a central and six pericentral cells; in the last-formed 
side-branches this number may sink to four, but as a rule it is six. The pericentral cells, 
in common with those of Endosiphonia and Melanothamnus, cut off to the outside cells 
quite as long as themselves; and this may be repeated several times. In the branches 
the cells on the dorsal side are a little longer than those on the ventral, but this difference 
disappears with subsequent growth. The whole central strand is surrounded bya rather 
thick layer of parenchymatous cells. The peripheral cells are of equal size and elongated 
longitudinally, not radially as in Melanothamnus. Though the cortical layer is pretty 
