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firmed in this opinion not only by the appearance of the 
luminous stratum or so-called ciliary wave which had been 
observed by Dr. Branson, Mr. W enham, and others, but also 
by the appearance on the cell walls of certain markings 
revealed by the action of the dye on the suspension of the 
vital action. 
The above experiment was exhibited to the Section, and 
many of the members present attributed these markings, as 
I had done, to the presence of cilia. 
I have since, from time to time, pursued my experiments 
on the subject in the hope that I might be able to adduce 
more positive evidence as to the cause of the wave of light 
on the interior of the cell wall. 
After many fruitless experiments I at length determined 
to try the effect of polarized light, and on the application of 
it with a ith-inch objective, having an aperture of 130° to 
162°, and so arranging Barker’s series of selenite plates as 
to give a dark blue ground, there appeared over the surface 
of all the cells brilliant gold-coloured scintillations which had 
all the appearance of cilia in motion. 
The portion of leaf under examination exhibited very 
sluggish circulation, and was therefore in a very favourable 
state for the observation. 
I have since repeated the experiment several times, and 
have never failed witnessing the same appearance. 
Notwithstanding all that I have seen I cannot say that I 
am convinced the appearances can be attributed to nothing 
else but cilia ; it is possible they may be due to the pre- 
sence of active corpuscles, as suggested by Mr. Wenham in 
his paper on the leaf cells of Anacharis alsinastrum pub- 
lished in the Microscopical Journal for 1855, which cor- 
puscles may be Yibrionia or Zooglaea, described by Dr. 
Cohn in his “ Researches on the Development of the Micro- 
scopic Algae and Fungi,” as representing the developmental 
condition of a plant, but it is only by further research that 
this point can be definitely settled. 
