surface of the membrane, their destination might be con-
jectm-ed. The delicate and tender membrane itself might
be regarded as the matrix for the developement of these
granules, Avliich, when mature quit it, and join the other
granular bodies contained in the circulating fluid, and the
nature of Avhich is itself probably determined by their presence.
That the granules studding the inner membrane do
in some Avay or other enter the circulating fluid, is rendered
highly probable by the fact that the majority of particles
Avhich it contains bear a close resemblance to these granules.
Mr. Varley fu rth e r remarks in reference to these granules,
th a t if any of them, situated in th e middle p a rt o f a cu rren
t, be disturbed by injury, no effect is produced, th e
stream passing on as before; b u t th a t i f th ey be displaced
over th e boundary lines, a communication takes place between
the two c u r r e n ts ; a portion of th e fluid ne a r the
boundary line, instead o f passing on to the end of th e cells,
crosses over it into th e re tu rn in g current, and passes on
w ith it, a portion o f the descending, in like manner, jo in in g
th e ascending and folloAving its course. “ I believe,” says
Mr. Varley, “ th a t in this case th e fine membrane is no t
wounded, b u t is probably loosened from its adliesion to the
ridge, th e green vesicles only being removed or in ju red :
b u t it shows th a t th ere is a most in tim ate connexion betAveen
these vesicles and th e c ircu la tio n ; and th ey appear to
govern the c ircu la tio n ; for in th e case above stated, where a
clear space was refilled with green vesicles anastomosing
had tak en p la c e ; h u t when th e spot Avas again coated w ith
vesicles, th e anastomosing also ceased, th e fluid having
again tak en its direct course, coinciding correctly with th e
track marked ou t b y th e ir arrangement. I am led to th in k
th a t any Avound of th e membrane Avould kill th a t whole cell,
by submerging th e vesicles in th e th ick or th e in n e r fluid, and
th u s c u ttin g off th e continuity of th e ir action, or by th e
different fluids mixing and so destroying th e ir action. T h e
fine membrane Avith th e vesicles is seldom removed fa r
enough from th e tu b e to shcAV th e colourless space hetAveen
(though I have samples before me now that shew It) ; therefore
the fluid which passes between the vesicles must he
very small in quantity, and is so limpid as to be difficidt to
discover.”
In what way the removal or injury of the granules, placed,
according to Mr. Varley, on the outer surface of the membrane
can influence or govern the circulation carried on
within tha t membrane, it is difficult to conceive. I t seems
to me, tha t the anastomosing of the currents can only be
accounted for by adopting the view of Mr. Slack, relative to
the internal organization of the Characeoe to be mentioned
presently, or by supposing the internal membrane to be
ruptured in the situation of the boundary line, thus permitting
an escape of the circulating fluids from the interior of
the membrane to its exterior, and so deranging the disposition
of the granules.
W ith in th e laembrane which has been ju s t described is the
proper eirculating fluid o f th e plant, which, in full motion, is
dense and th ick , tho u g h tran sp aren t, containing a variable
number o f solid granules, Avhich circulate w ith it in the
course already indicated from le ft to right. T h e granules
do not, however, all move with equal velocity, or in a procession
as it were.
Internal to this fluid, and occupying the centre or nvis
of the cell is another fluid, almost quiescent, and usually free
from solid admixture. This is generally greater in quantity
than the former or circulating fluid.
“ These two fluids being of different densities,” according
to Mr. Varley, “ do not when the plant is in health
mingle, and are not separated by a membrane. According
to Mr. Slack, however, a membrane does exist between the
different fluids, enveloping the central, and forming an
axis for the circulating fluid to revolve on, usually becoming
attached in the course of the longitudinal boundary lines,
thus separating the two currents of the circulating fluid
from each other. I t can now be understood in what way
injury to this membrane, if it really exist, would occasion the
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