S lurch.— Harvey el la mirabilis ( Schmitz & Reinke). 91 
Since, at the same time, the remaining peripheral cells have 
continued to grow, the young carpogonial branch is soon 
more or less buried in the frond. The carpogonial branch 
invariably consists of three small cells, upon which is seated 
the carpogonium with its trichogyne. The carpogonial branch 
is always attached to a cell of a peripheral chain, about one 
to four cells beneath the distal cell (Figs. 8 and 9). Soon 
after the appearance of the three small cells, the carpogonium 
becomes produced downwards at the side of this carpo- 
gonial branch (Figs. 9 and 10). At this time the trichogyne 
is also somewhat swollen at its upper extremity. While the 
trichogyne is developing, the frond still continues to grow 
at its periphery, and so the carpogonium slowly becomes 
more deeply buried in the frond, and when mature it is 
usually about four cells from the surface. The trichogyne 
continues to elongate until it reaches the surface of the 
external membrane of the frond, which it usually pierces 
without bending ; but occasionally trichogynes are seen 
which, instead of breaking through this membrane, become 
bent and grow between the external peripheral cells and 
the outer surface of the membrane, and thus never reach the 
exterior. When the trichogyne has pierced the membrane, 
it grows for some distance beyond (Fig. 10), while the carpo- 
gonium continues to grow downwards at the side of the 
carpogonial branch. During the development of the tricho- 
gyne, the cell of a peripheral chain to which the carpogonial 
branch is attached increases in size and cuts off two small 
cells from its basal part, one on each side. These two cells 
rapidly develop into two short filaments, one of which 
consists of four cells — a 3-celled filament with a 1 -celled 
branch from its proximal cell— and the other of two cells 
only (Fig. 10). Of these two filaments, the one consisting 
of only two cells is generally, if not always, attached nearer 
to the basal end of the peripheral cell from which they spring. 
This peripheral cell, to which the carpogonial branch is 
attached, is the auxiliary cell, and it invariably gives rise 
to these two small sterile filaments before the trichogyne 
