Monthly Microscoplcan 
Journal, April 1, 1869. J 
of Compound Leaves. 
219 
leaves of Umbelliferous plants, as Foeniculum, Lihanotis, &c. In 
these the parts develop basifugally ; but in Spirsea lohata they 
have a basipetal-cyclical development. 
To most of these types both simple and compound leaves belong. 
It is remarkable that a type seems to run in a natural order. For 
example : the Bosacede seem mostly to belong to the basipetal type, 
the Leguminosse to the basifugal, while the Banunculacem are emi- 
nently ternate. 
The study of leaf-development is very interesting, and not diffi- 
cult. The leaves are to be dissected out of the bud, and the youngest 
leaves will be found immediately underneath the growing point of 
the axis. They must be examined as opaque objects, with a power 
of about eighty diameters. It is best to mount them as opaque 
objects, and for this purpose cells of black sealing-wax are very 
useful. It is essential that the specimen be able to be examined in 
all lights ; and, if the stage of the microscope does not rotate on its 
own axis, the preparation is best mounted near one end of the glass- 
slide. The slide is warmed, and a little black sealing-wax placed on 
the end on which you propose to form the cell. Wax is added drop 
by drop, until enough has been placed on the slide. The central 
portion has now to be hollowed out to form the cell. This is easily 
done by means of a small brass-weight — the J oz. letter-weight 
answers admirably. It is pressed in the middle of the wax, which, 
rising on each side, forms a wall of wax surrounding the depression. 
The edges of the cell must be flattened ; this can be done by pressing 
another slide, which has been previously wetted, firmly and evenly 
on the edges of the cell. If a specimen is to be mounted, a small 
quantity of cotton- wool is placed in the cell, and the preservative 
fluid added — distilled water, acetic acid, and creosote answers well. 
The specimen is now adjusted with that part uppermost we wish 
shown, and the glass-cover carefully put on, so as not to disturb the 
specimen. This is the most troublesome part of the process, and 
if the specimen is once displaced it is very difficult to readjust it. 
The whole is then sealed in the ordinary way with asphalte. The 
specimens keep well, and I have some before me put up in 1865, 
which exhibit all the various parts as well as when first put up. 
VOL. I. 
R 
