258 THE WINTER STATE OF OUR DUCKWEEDS. 
some who often desire to make additions to the store of botanical 
morphology but who hardly know how to proceed. 
It is best to select some definite question concerning the case 
that one wants to study, and then with knife, needles, chemicals 
and microscope, compel it to yield an answer. It will give definite- 
ness and precision to one’s work. I started with this one: 
“ Where is the growing-point of this winter frond?” 
By Figs. 1 and 2, it will be seen that the object is almost 
exactly of the shape of a shallow plano-convex lens, the flat side 
being the upper side ; as I found some weeks after, when they rose 
and floated on the surface of the water. 
The outline is often slightly kidney-shaped, and at the sinus 
there is a scar on the edge, Fig. 2s. Sections show that the edge 
is here more obtuse than elsewhere. 
Around that point, on the flat surface, there was traced a wil 
semicircle. That was all that could be descried on the exterior. 
The disk was not at all transparent, so that all knowledge of its 
interior must be obtained by dissection. 
Laying the frond on the end of the forefinger, and holding it in 
place by a gentle pressure of the thumb, I made three or four slices 
lengthwise (that is in the direction of the Iines a—a, b-b, etc., of 
Fig. 2). From the tip three-quarters of the way to the base (as I 
shall call the scar end) all these sections were composed of simple 
parenchymous tissue (where cells are of nearly equal dimensions 
in all directions), whose cells were packed with starch grains. But 
the quarter next to the base presented very different views in the sev- 
eral sections, and appeared quite complex (Fig. 53). Two regions, 
Pa’ 4 a and b, attracted attention because of the fineness of the 
Fig. 53. tissue composing them. The cells 
a Wo A » æ in these parts were not more than 
| an eighth the diameter of the reg- 
ular cells of the frond ; neither were 
they filled with starch grains, but 
were well supplied with protoplasm, 
‘ with considerable chlorophyl. 
Here evidently was the place to search for my “ growing-point.” 
In that one of these regions furthest from the base, Fig. 4 a, and 
on the convex or under side of the frond, are one, two, or more oval 
ies whose axes of growth were nearly at right angles to the 
length of the frond. I took them for young buds. In each section 
i 
a 
: 
eN 
; 
Be 
oa 
; 
is 3 
A 
on 
af 
