mm
diffused light. The agitation has changed, as it Avould appear,
the regular order of the molecules of the liquid, and
their aggregation has become confused. In this last state
they enjoy a mobility of which they were deprived in their
state of regular position ; and it is to be remarked that water
so changed Avith a mineral substance in solution and agitated,
has more molecular mobility, and is more susceptible of circulation
than was the pure water before this solution.”
With the folloAving extract, this epitome of Dutrochet’s
letter on the circulation of Chara may be concluded : —
“ After having filled tubes Avith acidulated milky water
I have closed them Avith the lamp. This liquid being fit
for circidation, being unalterable, and not being able to lose
any thing by evaporation, it follows that being exposed to
the light it possesses the condition of a perpetual circulatory
movement, Avith nocturnal intermissions, and further, with a
Avinter intermission, Avhich exists but when the temperature
is inferior to 5° E. One might say, metaphorically, that this
liquid is, during the night, in a state of sleep, and during
the day, in a state of Avakefulness ; one might say also that
its repose in Avinter is a state o f hibernation. I t might be
supposed at first vieAV that these phenomena bore some analogy
to the state o f sleep and of wakefulness o f plants, and
to their state of hibernation.”
An experiment in reference to the circulation of the Characeoe
may here be referred to, viz. that the application of a
ligature to the centre of a cell does not destroy the circulation
therein.
This experiment was originally made by Easpail.
A general description having now been given of the
structure and circulation of Chara and Nitella, a feAV other
particulars still remain to be noticed.
A delicate membrane lines the interior of each cell,
having little or no attachment to the one which constitutes
the proper cell membrane, and Avhich is therefore easily
separable therefrom, save at the lateral colourless longitudinal
lines, which are formed probably by its attachment.
This membrane is studded over with a number of minute
granules, which impart colour and texture to the plant.
This inner membrane is represented in fig. 7. Concerning
these granules, Mr. Varley makes some curious remarks: —
“ The minute green bodies always adhere to the membrane,
and never to the outer tube. In some specimens these
green bodies are so regular as to leave only a very narrow
and even partition, whilst in others, the green studs are very
scanty and irregular at the parting lines, appearing rather
scattered about, as shewn in fig. 11. In such places, if
the green bodies be patiently watched through a doublet
1-6 0th focus, they will be seen occasionally to expand and
contract, change their form, move a little round, then more,
and then go on to a whole tu rn or more; move forwards a
little, and sometimes start off out of the field; some I have
followed till they stopped behind stationary ones, and I have
seen some come into the field and be stopped; also minute
darkish dots are seen running along between these studs,
and some of these would turn aside as by an eddy, and
stop between them. Again, whilst writing this, I have seen
some (where an open space had been made by bending
or teasing the stem) move forwards, and then r e tu rn ; three
or four separate ones came together laterally, then went
forwards close to the regular and undisturbed ones; they
then, after stopping some time, came back, and parted a considerable
distance from each other, and with the motion of
others, they were lost to any further observation, and the
next day all the irregular ones had moved, and some parts
assumed a more regular arrangement.” The singular movements
above described correspond precisely with those of
the Zoospores described in the Introduction, to which, in other
respects, one would not suppose them to be analogous.
Mr. Varley considers these green granules to be placed on
the external surface of the inner membrane, to which, from
their power of locomotion, they must be supposed to adhere
but feebly. The purpose which they serve in such a situation,
it is not easy to determine: were they adherent to the inner
G 2