296 THE MICROSCOPICAL NEWS. 
7 
tion the colour of the field of view stands out, and at the same 
time the pore-canal, which is revealed under — 45°, appears in blue; 
and these colours are inverted if we change the position to go’, z.¢., 
where yellow was before, blue appears, and vice versd. This fact 
confirms the change of the ellipsoidal section represented in Fig. 
4, and also the uninterrupted course of the inner layer through the 
entire hollow chamber of the cell, including the pore-canals with 
the inclosing wall, as it is represented in Fig. 3. 
Through chemical influence (to which I will refer in my next 
work in another place), the inner layer is loosened, and the adjoin- 
ing closure-wall disappears; thus the inner walls of the dilated 
4 5. 
pore-canal, into which now the secondary thickening directly flows, 
do no longer show the aforesaid colour-difference ; on the contrary, 
all the wall-layers, not having shared in the separation, and having 
remained nearly as strongly doubly refracted as before, appear 
coloured yellow or blue, according to their position under + or 
as ie 
Extremely striking results are afforded by polarized light when 
spectrally dissected. With the previously considered object (trans- 
verse section of Pinus sylvestris), in the parts of the transverse 
section lying above the dark Miiller’s band (produced in the green 
of the spectrum, through a small red selenite-plate, with the centre 
near Fraunhofer’s line 4), the singly refracted cambium-wall appears 
most distinctly as a dark stripe between the primary walls, shining 
in the most brilliant green; whilst the other parts, lying over the 
colour-regions of the spectrum not affected by the selenite-plate 
(and indeed lying in the regions where the colour of the selenite 
