Short Papers and Notes. 27 
down like the surging ocean, and where not even a lizard could 
have dared to show its face. Thorns cannot be, so I have thought, 
for protection where the climate gives all the protection desired. 
I am not one who doubts that Nature has a purpose in every move 
she makes, but the main purposes I think we seldom reach, and 
that we do ourselves an injury in research by assuming mere incl- 
dental uses as the main purposes for which structures seem to be 
- “adapted.” 
One of these uses in the spines of cactus has occurred to me. 
They break the full force of the sun on the plant, a force it is 
made to endure and not to love, as we know who have learned to 
cultivate it. Plant-lovers set out their treasures in summer under 
“arbors” of fish-netting or galvanised wire, and those who have 
no experience would be surprised to find how the moving shadows 
of the twine or wire lower the temperature. A mass of spines on 
a cactus must have the same effect. A cactus does not need 
much light on its epiderm to keep healthy. On the dry mesas 
along the Uncompahgre River I have seen some aggregated masses 
of Echinocactus pheniceus forming dense hemispheres a foot high 
and as much wide, with spines so thoroughly interlaced with spines 
as to rival the hedgehog, and leaving not a particle of the green 
surface visible; and there are species not cespitose, such as &. 
pectinatus, which no one can see for spines without cutting apart, 
and forming a complete protection from the hot suns under which 
they are doomed to live. 
I do not suppose I have yet reached the final purpose of spines 
in a cactus any more than we have the final purpose in the exist- 
ence of the cactus itself, but that one use of cactus spines is to 
furnish a partial shade I feel to be beyond a doubt.—Thomas 
Meehan, in Bull. Lorrey Botanical Club, 
Short Papers and Notes. 
ZL Lesson trom the flowers. 
HE inevitable result of excessive display is impoverish- 
ment and degeneration. Some plants which have blos- 
somed beyond their strength grow weak and die. The 
pretty lady’s-mantle, the violet with its retiring flowers, 
and many other familiar ornaments of the garden and 
field, present unmistakeable evidences of retrogression. It is 
well ‘known that bulbous plants, such as the lily or tulip, will not 
produce nearly such fine flowers if left to blossom year after year 
