THE WINTER STATE OF OUR DUCKWEEDS, 259 
one was larger than the rest. I took it for the main bud, and sup- 
posed that its extremity was the growing point of the plant. To 
- get a better view of its tip, that I might make out the plan of cell- 
division at the point where the cells were first formed, I made 
some new sections in the same direction, much thinner than the 
first. On examining these I recognized the cell arrangement pe- 
culiar to the extremity of roots ; there plainly enough was the root- 
cap, Fig. 4 d, and tlie “ summit” cells or region, Fig. 4 c, where by 
cell-division the new growth is produced. These were surely the 
rudiments of young roots. I must look elsewhere for the plumule 
with its growing point. But one thing had been learned ; my little 
disk contained roots, and I knew where they were. 
The other spot where the cells were small and tinged with green 
seemed without any regular shape. One section showed one thing, 
another quite a different thing; while in another there would be. 
nothing but a hole where the fine cells ought to be. 
See the differences in the five sections of Fig. 53. These sec- 
tions were made through the lines marked a-a, b-b, etc., of Fig. 2. 
As the next step I made some sections at right angles to the 
former in the directions A-A, B-B, etc., of Fig. 2 (see Fig. 5), and 
got one new idea at least. Instead of there being one body in the 
place occupied by “ b,” Fig. 4, there were two, one on either side 
of the median line of the frond, and the two were very unequal in 
size, though somewhat similar in form. But, although diligently 
comparing the views presented by the two sets of sections, I could 
not form any satisfactory idea of these portions. The two sections 
D and E, of Fig. 5, showed quite clearly the number and position 
of the young roots. The darker spot which appeared in the last 
three sections, marked “ s” in “ D,” Fig. 5, was anew mystery. I 
must have sections in the third plane also, that is, the plane pass- 
ing parallel with the surface of the frond. | 
And just here let me say a word about making sections of deli- 
cate vegetable tissue. I have found it much better in all cases, 
except where the position and structure of the protoplasm are in 
question, to soak the specimens in glycerine, first in diluted and 
finally in strong. One advantage is this; when making sections 
of soft tissues in water, there is great danger that a thin section 
on the blade of the razor will dry up and be spoiled, while attend- 
ing to the piece on one’s finger, which ought to be taken off immedi 
ately and laid in water. Or if one first cares for the section on the 
. 
