45 
water is reached. A glass slip having a shallow cavity or cell in 
the center is very useful in examining these thin sections, which 
when placed in the cell are not liable to be crushed by the cover 
glass 
If bast-bundles be present and the sections be sufficiently- thin 
they will then be seen by transmitted light and under a magnify- 
ing power of 300 diameters, as a bundle of brown cells, quite dif- 
ferent from the cells of the epidermis. A bundle of bast cells in. 
the center of the leaf is to be seen in all species. The peripheral 
bast cells are located in our species as follows : When four are 
present, three will be found on the upper or ventral side of the 
leaf — one at each end and one midway — and one in the center of 
the dorsal or lower side, all of them being close to the epidermis 
When two only are present, those at the terminations of the ven- 
tral side are wanting. 
Leaves or whole plants of the quill worts can be preserved in 
good condition for any length of time, if kept covered with alcohol 
or an aqueous solution of formaline, the latter being preferable in 
situations where it is not liable to freeze It is quite possible how - 
ever to detect bast-bundles when present, in the leaves of pressed 
specimens, the sections by boiling resuming in a great measure 
their original form A small test tube such as is used by chemists 
when held in the flame of a lamp, serves a good purpose in boil- 
ing section of Isoetes leaves. 
Great care should be taken in drying and pressing the larger 
plants of this genus. The dryers should be frequently changed, 
and if the specimens are very large and filled w T ith moisture, they 
should be divided through the trunk by making a section at right 
angles to its natural division. The trunk in all our species is nor- 
mally bilobed bu4 individual plants are found which are trilobed. 
this occuring most frequently with I. Tuckermani . 
