110 
Osborne^ on the Wheat Plant. 
carefully made through this substance, in a direction which 
will include the lower part of the plumule and the commence- 
ment of the roots_, we get a view of the basis of the whole 
vascular system. A large number of pitted cells are seen, 
some passing downwards to branch out into bundles, one to 
every root ; these, as soon as they reach the base of a root, 
assume a modified scalariform appearance ; others branching 
upwards to the leaves assume either the spiral character or 
that of a double band, of which one part is scalariform, the 
other annular, or the broad spiral breaking up into rings. 
The origin of all these vessels would seem to be similar — cells 
of a long, ovate form, so indented or pitted, that with proper 
illumination their surface presents a reticulated appearance 
(PL V, fig. 37) ; where they join at their extremities they 
widen, their intermediate walls absorb, and thus one long 
vessel is produced by the conjunction of many distinct cells. 
Turning now from general structure, I will enter more into 
detail as to the formation of those cells of which every vege- 
table structure is composed. 
If a seed of wheat is permitted to so far germinate, that the 
plumule and roots are thoroughly developed, it wiU, by pres- 
sure upon a glass slide, give out a certain amount of milky- 
looking matter. If this matter is mixed with a few drops of 
distilled water and spread out over the surface of the glass, 
as it dries up I have ever found it to assume the same appear- 
ance — that of nearly parallel lines connected at irregular 
distances by curves, presenting an appearance of the form 
and character of cellular tissue. I only mention this fact, as 
one that, with others, has led me to believe that the formative 
matter of a seed in this stage of germination has a direct 
tendency to resolve itself into a form characteristic of the 
tissue which is so wonderfully to be educed from it. As far 
as I can trace the changes within a seed germinating, it 
appears that, by the breaking up of its outer tissue, the 
moisture requisite to decompose its contents is admitted. 
The granules of the starch now burst and become mere 
vesicles, having exchanged their normal outline for one more 
oval; their concentric markings and hilum, for a plane 
surface extensively lacerated by that bursting of their tissue 
which has liberated their contents. The formative fmid at 
this stage is found full of these torn vesicles of the starch 
granules, with a large amount of glutinous and also of active 
molecular matter. 
In the next more advanced stage of this matter I obtained 
some of my best specimens by the following simple means : — 
I put a certain quantity of the milky matter expressed from 
