Ctje popular Science 0tM>s 
AND 
BOSTON JOURNAL OF CHEMISTRY. 
YOLUME XXY. 
BOSTON, OCTOBEE, 1891. 
Number 10. 
CONTENTS. 
Familiar Science. — A Carnivorous Plant . 143 
Glaciers 144 
A Universal Stand 145 
A Novel Current-Breaker 145 
The Development of Devices for Cross- 
Fertilization in Plants 146 
An Hour in the Botanical Gardens of Padua 146 
Alchemy 147 
Invisible Photography Made Visible . . 147 
The Out-Door World.— Chapter Addresses, 
New and Revised 148 
The Agassiz Association at the World's 
Fair 148 
A Corresponding School of Chemistry . . 148 
The Council of the A. A 148 
Itevised List of the Council 148 
The More Letters the Better 149 
Original Observations by Members of the 
Agassiz Association 149 
Simple Botanical Apparatus 149 
Five Hundred and Sixty-seven "Sweeps'" 
in One Chimney 149 
Agassiz Day at Avon-by-the-Sea .... 149 
Outings of the Barton Chapter .... 149 
A Corresponding Entomological Chapter . 149 
Reports from Chapters 150 
The Blue Mountains 150 
Editorial.— 'i'he Recent Scientific Conven- 
tions in Washington 151 
Photography with a Black Background . 153 
I'aris Letter 153 
Meteorology for August, 1891, with Re- 
view of the Summer 154 
Astronomical Phenomena for October, 1891 155 
Questions and Answers 1.55 
Literary Notes 155 
Medicine and Pharmacy.— The Future of 
Medicine 156 
Monthly Summary of Medical Progress . 156 
Cutaneous Geromorphism 157 
The Natural Size of the Waist 157 
The Significance of Muse* V'olitantes . . 1.58 
The Old New England Doctor 1.58 
Medical Miscellany 158 
Publishers' Column 158 
9amiliap ^eienee. 
[Original In Popular Science News.J 
A (JARNIVOROUS PLANT. 
BY S. L. CLAYES. 
Til eke are certain plants which seize and prey 
upon insects. The fact of the capture is beyond 
doubt, and the plants which are capable of this 
feat are known generally by the name of fly- 
catchers. But while many fly-catchers can make 
no claim to being fly-digesters, there is among 
them a class of plants which, to all appearances, 
possesses the power of assimilating animal food 
and being nourished by it. 
One of the most conspicuous of this group is 
Diontjea muscipula, the Carolina catch-fly, or Venus 
fly-trap. It is a native of the Southern States, 
North Carolina being, I believe, the northern limit 
of its growth, and, like so many of its species, it 
always finds its home in some bit of marshy land. 
To attain true success in its artificial cultivation a 
pot of bog earth is required, which should be kept 
constantly standing in a deep saucer ot water, 
The appearance of this plant is so peculiar that 
when once seen it is not readily forgotten. A 
leafless scape, six inches in height, rises from the 
root, and terminates in an umbel of white flowers ; 
these are, however, of distinctly subordinate in- 
terest. Its winged leaf-stalks spread themselves 
out like a kind of rosette about the root, each 
bearing a broad leaf, so curious in the strange 
powers which it displays as almost to convince 
one that the plant can lay claim to a sentient life. 
The leaf proper is orbicular in shape, and has a 
hinge-like raid-vein, upon which the halves swing 
smoothly, opening and shutting with great speed 
and ease. Each half is somewhat concive upon 
the upper surface, and is bordered by a row of 
spines thickly placed around its outer edge, and 
set iit sucii an angle as to cross when the blades 
are closed. They have, also, a power of separate 
movement, and interlock like the fingers of two 
liands. They remind one irresistibly of the teeth 
of a steel trap, which, in fact, they also resemble 
in the use for which they are designed. On the 
central part of each blade we find three conspicu- 
ous hairs. These are of the gieatest sensitiveness, 
delicate, irritable, and so placed that even a small 
insect can hardly alight or move abo\it upon the 
leaf without touching one or more of them. Over 
tlie surface of the blades are also strewn many 
small red globules, or glands, which are most nu- 
merous in the vicinity of the hairs. Provided the 
leaf upon whicii it grows be vigorous, no sooner 
is one of these irritable hairs touched — be it never 
so lightly — than the blades spring together, the 
spines cross at right angles, and presently a 
sligiitly glutinous secretion begins to flow from 
the red globules, which is supposed to be the 
active agent in the process of digestion. It is not 
improbable tliat the fluid from these glands may 
also serve to attract insects and cause them to 
alight upon the plant. While it is not well to 
often touch these hairs, and thus provoke the leaf 
to close, — for much handling seems in a measure 
to weaken its powers, — we can watch this action 
in other ways. 
On a warm day in summer we may reasonably 
count upon finding our fly-catcher with a keen 
appetite and alert for opportunity. Its red glands 
glisten in the sun, and a fly, espying the pretty 
sight, and maybe attracted, too, by some odor 
suggestive of delicate feasting, alights upon the 
leaf. Perhaps at his very first step he brushes 
against one of the sensitive hairs, when the two 
halves instantly close. Even were the process 
less prompt than it is, or the leaf imperfectly 
shut, the fly would be captured, for the interlock- 
ing marginal spines form such a network above 
the poor insect as to eftectually prevent his es- 
cape. In his efforts to find a way out he will run 
up and down, and be sure again and again to 
come in contact with the hairs, which, proving 
each time responsive to his touch, even more 
tightly lock the walls of his prison about him ; 
while the force of the contraction is so great that 
should he put forth .all his power of strength it 
will 1)C ill vain— he cauuot force them open. 
Now the leaf is shut, but on a close examina- 
tion we find that the blades really touch only at 
their margins, and that a hollow space of consid- 
erable size is left open in the center. By holding 
the leaf against the light we can see the impris- 
oned fly nervously moving about all over this 
space in anxious search for some means of deliv- 
erance. If he be not of too great size, the saucer- 
like form of his cell at first saves him from serious 
pressure. For a while there seems to be nothing 
more amiss with the little creature than being 
deprived of his liberty. When at the end of two 
or three hours his leaf has been forced open, he 
has usually, after a moment of bewilderment, 
been able to fly away as if all things were well 
with him. It is uncertain how long the captive 
may be held alive within these prison walls. ' I 
have seen one moving about after more than fifty 
hours. After an imprisonment of two days the 
fly h.as been liber.ated and found to be still alive ; 
but the poor insect under these circumstances has 
never recovered. It is a hopeless task to attempt 
to save him when once he has been bathed in 
the fluid from tlie glands. Although he may be 
cleansed with the most delicate care, and every 
particle of the viscous stuff" appear to be washed 
away, the poison seems to have entered his sys- 
tem, and the poor creature is doomed to succumb. 
When the fly is not removed, and matters are 
allowed to take their natural course, the two 
blades of the leaf continue to pass more and more 
closely together, until they actuiilly touch each 
other, so far as the body of the insect — or what 
remains of it — will permit. 
The mucilaginous fluid discharged by the glands 
yields, upon examination, some formic acid, and 
it also contains a substance very like pepsin. By 
its aid a portion of the fly"s body is digested, and 
the digested mass is absorbed by these same ver- 
satile red glands which produced the fluid, and 
which have in their interior certain formations 
that botanists call stomata, a name which is de- 
rived from a Greek word signifying mouth. 
The process of digestion in the plant, far from 
being hurried, is one of the greatest deliberation. 
The time occupied varies from one to three weeks, 
its duration being influenced somewhat by the 
size and vigor of the leaf, but far more by the 
kind of food which is being absorbed. Soft- 
bodied insects, flies, spiders, and those of like 
texture are more quickly disposed of than beetles 
and others which have hard or shell-like cover- 
ings, and small creatures disappear more speedily 
than larger ones of the same sort. The size of 
the insect thus caught and capable of being di- 
gested seems also to bear direct proportion to the 
size of the plant. Experiments tried upon an 
unusually large specimen of Venus fly-trap have 
been most interesting in their results. One leaf, 
measuring one and five-eighths inches in length 
from end to end, and three-fourths of an inch 
from mid-rib to edge, with spines one-half inch 
long and numbering nearly four dozen in all upon 
the two halves, caught and consumed not only 
lormiduble spiders, but a horny beetle as well. 
