TEACHERS DEPARTMENT. 
305 
We are, I believe, to look for the cause of thorns in these plants 
to some inherent quality of the plants themselves. There are 
certain families of plants that run to thorniness and several of 
these are centered around the rose family. There are many 
thorny species among the legumes and in the rose family, to 
which the hawthorn is most closely related, e. g., blackberries, 
raspberries, roses and others. It seems to me the reason why 
these plants produce thorns and prickles is because “ it is their 
nature to.” 
THE TEACHERS DEPARTMENT. 
Edited by Professor C. Stuart Gager. 
The Following Notice has been received from the U. S. De¬ 
partment of Agriculture, under date of November 25, 1905. 
The fiber exhibit of the U. S. Department of Agriculture at the 
Louisiana Purchase Exposition consisted in part of commercial 
bales of plant fibers such as are used in the manufacture of yarn, 
thread, twine, cordage and woven goods. These bales have now 
been broken up into samples, with labels stating origin, prepara¬ 
tion, and use, and are being distributed to schools and colleges for 
use in teaching economic botany and commerical geography. 
Sets will be furnished for school use upon application to the 
Office of Fiber Investigations, U. S. Department of Agriculture, 
Washington, D. C. 
Another Root Cage.—A simple and effective root cage may 
be made from a wide lamp chimney. Get the largest size, and in¬ 
vert it in a dish: fill with earth (or sand) to the widest part, and 
then plant the seeds near the edge. On account of the sloping 
sides the roots will run down in contact with the glass. Such a 
root cage costs only ten cents and is as good as any that I have 
used. Charles E. Bessey. 
Demonstration of Masked Chlorophyll in Frond of 
Laminaria. —If a frond of Laminaria of desired length, after 
being simply air dried, be passed with moderate rapidity through 
a Bunsen flame, at once the brown coloring matter (phycophaein) 
