276 ABBEY, ON ORGANIC STRUCTURE. 
gorged with nuclear matter, and that the fibro-vascular bundles 
seem perfectly formed, but that the spiral vessels are the only 
parts somuch as tinged by the magenta. This accords with 
the fact, familiar to botanists, that these vesssels are the fore- 
runners of the “ bundles.” 
If, on the other hand, we take a second year’s shoot from 
some shrub, we see that the new deposit of woody tissue is 
much more intensely coloured than that of the preceding 
year. Returning to our Rumez, and taking a slice from an 
older stem, we observe that the cells of the medullary rays 
and of the peripheral portion of the central parenchyma have 
become thickened by woody deposits, and that these latest 
productions are more deeply magenta-stained than the pre- 
viously lignified pleurenchyma of the fibro-vascular bundles. 
This useful peculiarity of behaviour may readily induce 
error on the part of a careless observer. To illustrate this, I 
must for the moment digress into the animal kingdom. If 
a section of bone-cartilage be dyed with magenta alone, it 
will present the “ cartilage-corpuscles” (nuclear matter) as 
bright pink upon a very much paler ground. Reference to a 
similar section dyed with magenta and the aniline-blue sub- 
stitute for carmine will explain the apparent inconsistency, 
by showing that the nuclear matter is enclosed in a film of 
recent ‘‘ formed matter,” which takes a deeper stain from the 
magenta. 
Useful indications might probably be derived from the fact 
that the magenta is often more or less deoxidized by the 
tissues which it dyes, becoming more purple. The liber 
seems to be exempted from this action, and to be always pinker 
and less deeply coloured than the spiral fibre or the woody 
tissue. There is a peculiar form of cell-thickening, corre-- 
sponding, perhaps, to the variety of liber stated by Mohl to_ 
consist of cellulose, which, during some part of its existence, 
at least, takes no colour. I am not, however, able to give 
its history. 
Some one—I forget who—has proposed the contents of a 
rhubarb-tart as a ready means for obtaining spiral vessels. 
If these, thus obtained, be dyed with magenta and carmine, 
well washed, and mounted in balsam, the microscopist will 
find himself in possession of a preparation that is both 
instructive and beautiful. The fully formed vessels will be 
found to vary as to the degree of juxtaposition of the 
successive coils of fibre. In some the spiral will suddenly 
break up into rings, or divide to form a second spiral winding 
in the same direction; but in all these a cell-wall of the 
most limpid transparency encloses a crimson spiral, and 
