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282
ance of such a body »is the herald of every local development».
hor has untertaken to study the origin of these bodies. She says
that one end cell »takes on a heavy mucilage coat»; this is the
only feature by which it can be distinguished from other cells or
from young hairs. Like them it divides and forms a short cell
row; but apparently this is not ils only mode of origin, for in fig.
14 RoE presents »two initial rows which are modified young hairs»;
fig. 11 shows a pear-shaped body terminated by a typical hair;
in fig. 8 the inilial is borne by a cell row which in no way differs
from others in this region, and, finally, in fig. 9 is an initial cell
situated laterally on a hair high
above its base. All the cross walls
in the »initial row» are then
resorbed and the nuclei dis-
appear. The terminal part re-
tains ils shape and becomes the
pear-shaped head, while the
lower part becomes filiform
from pressure; this is the taillike
appendage with a narrow, some-
limes almost invisible lumen.
Thus, the initial is transformed
into the mature structure as
described by MıTtcHELL and
WHITTING.
If Roe’s observations are accu
rate, there is nothing in the
whole class of brown algae that
zone, X c. 400. c. »Initial» penetrating presents the slightest likeness
older cortex, x c. 400. to this peculiar structure. Hav-
ing some general idea of the
group, I undertook to study the apical region of Splachnidium in
some detail. Years ago I made microtome sections of the 1908
material; this being rather advanced (almost without hairs) I made
numerous hand sections of the new material while Professor
O. Juer kindly prepared the microtome sections for which I tender
him my best thanks. The study of Splachnidium was finished in
the Jodrell Laboratory of Kew, and I thank the Keeper, Mr.
BoopLE, for kind assistance.
I am unable to confirm RoE’s statements. I have studied nume-
Fig. 3. a, b. »Initials» in the growth-
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