260 THE WINTER STATE OF OUR DUCKWEEDS. 
razor, then the piece from which it is cut may be spoiled. But 
when the object is in glycerine, plenty of time can be taken to care 
for both without any injury coming to either. I have found a good » 
razor the very best thing to cut with, much better than any lancet 
or small dissecting knife. 
' Let the thumb-nail of the left hand be cut short enough that the 
blade of the razor may rest against the flesh of the end of the 
thumb, while the object to be cut rests on the forefinger and is held 
in place by the thumb. You can then draw the razor very evenly, 
it being steadied by the thumb. The thickness of the slice can be 
regulated by pressing the razor less or more against the yielding 
flesh of the thumb. Especially is this the case when several sec- 
tions are made one after the other by as many drawings of the 
razor, each time pressing it a little more against the thumb-end. 
In this style. of cutting, the hand should be so held that the surface 
of the forefinger, on which the object is laid, should be horizontal ; 
but when a thin object is to be split parallel with its surface, I 
have found it best to turn the hand, after the object has been placed, 
as before, between the forefinger and thumb, so that the surface of 
the finger on which the object is lying should be vertical: you see 
then the edge of the object to be split. The edge of the razor must, 
of course, be also a vertical line. It is essential, in this case, that 
the object be placed far enough back from the ends of the finger and 
thumb that the razor blade may come between them and be guided 
and steadied by its contact with them. 
Having brought the edge of the razor in contact with the object 
to be split, draw the razor downward, bringing at the same time the 
heel outward (towards the right) and the point inward, making 
the part resting between the thumb and finger the centre of this 
slight rotation. 
During this operation I have found it best so to hold the hands 
and head that the eye sights right down the edge of the vertically 
held razor, for then the razor edge can be placed very truly against 
the exact portion of the object to be split that you desire. 
_ Resuming now our investigation of the duckweed ;— I sliced the 
frond into three or four sections parallel with its surface, and, 
placing them under the microscope, order seemed to be emerging 
out of chaos. To the right and left of the middle line of the frond 
= - were two cavities, one of them almost filled with one of the small 
celled bodies, Fig. 6 rb, while the other was not more than one- 
A 
