EUROPE AND NORTH AMERICA. 7 
wise the stems are sure to be broken; quick transference to the 
press, and a frequent change of drying paper, will usually ensure a 
satisfactory result. 
We may point out to the tyro a few other characters by which 
our plants are distinguished from the true mosses. If we examine 
a single stem we find that the branches are in fascicles or clusters, 
i.e. spring several together from one point, and at the top are 
closely packed in a roundish head or coma; if we look at the 
leaves of one of these branches under the microscope, we find they 
consist of a network of large empty cells which contain threads 
winding spirally round on the interior of the membrane, and are 
bounded by a dark line of narrow cells filled with chlorophyl; the 
capsule also is sessile on the dilated end of a naked branch. For 
the determination of species, however, a more minute examination 
is necessary, as besides the form of the various leaves we also 
require a knowledge of their internal structure, as well as that of 
the stem ; this is obtained by transverse sections of them, suffi- 
ciently thin to allow the light to be transmitted, and these are 
best examined in water and uncovered. 
The simplest mode of making the sections is to enclose the 
wet stem or branches in a split vial cork and tie them tight, then 
with a razor to make very thin slices of the whole, placing them 
in a few drops of water on a slide, when they will immediately 
expand and the cork may be picked out with a needle. Russow 
recommends that the whole plant be soaked in thick mucilage and 
allowed to dry, and then cut with a razor into water. Certain 
reagents are also of use in the examination of cell structure, as 
iodine and sulphuric acid, or a solution of biniodide of zinc, by the 
action of which the Sphagnum leaf is coloured blue or reddish, 
and all its details of structure sharply defined. Heating the leaves 
on a slide in a little liquor sodz is of value in enabling us to obtain 
a clear view of the outline and condition of the walls of cells. 
For those who have time and the necessary skill, the various 
parts may be mounted permanently on slides in glycerine, or other 
fluid suitable for vegetable tissues, and they then form very useful 
objects for comparison with any specimens which may be the 
subject of examination.* For the herbarium, it is better to 
separate the tufts into thin layers before submitting them to 
* The Rev. Mr. Vize, of Forden Vicarage, Welshpool, has put up sets of the 
British Sphagna mounted in this manner. 
