Che j^opular Science 0tXiis 
AND 
BOSTON JOURNAL OF CHEMISTRY. 
Volume XXV. 
BOSTON, AUGUST, 1891. 
IS'tjmber 8. 
CONTENTS. 
Familiar Science. — Tlie Office of the Green 
Plant Ill 
Animal Pirates ]1'2 
Woorali Poison 112 
Comparative Plant Morphology .... 113 
The Spirograph . 113 
Epilobium 114 
State Interference with the Fuilividual . . HI 
Identification of More Ancient Cities of 
the Pharaohs 1 14 
Industrial Memoranda 114 
Scientific Brevities 11.5 
The Out-Uoou World. — Ex Uno Disce 
Omnes 11,5 
Cuvier Natural History Society .... 115 
Beetle, Spider, and Toad 117 
Peculiarities of Scallops 117 
A Bird Drummer 117 
An Ancient Quarry 117 
Will Answer all Letters 117 
The Chemistry of Minerals 117 
A bare Fossil 117 
Frog Eats Frog 117 
A Schoolboy's Composition on Bones . . 118 
List of the Plants of the District of Mos- 
chaisk. Government of Moscow, IJussia . 118 
List of the Birds of the District of Mos- 
chaisk, Government of Moscow, Kussia . 118 
List of the Lepidoptera of the District of 
Moschaisk, Government of Moscow, Rus- 
sia 118 
Editorial.— 'ITie Giant Sloths of the Past . 119 
Hieroglyphic Inscriptions of Egypt and 
Palestine — How Head, and by Whom 
Discovered and Deciphered 120 
Paris Letter 121 
To Photograph Living Birds 122 
Meteorology for .lune, 1891 122 
Astronomical Phenomena for August, 1891 123 
Questions and Answers 123 
Literary Notes 123 
Medicine and Pharmacv.— The Electrical 
Executions 124 
Disease-Producing Jlicrobes 124 
The Sterilization of Milk 124 
Monthly Summary of Medical Progress . 125 
Medical Miscellany 126 
Publishers' Column ". 126 
^amiliap ^Gienee. 
[Original In PopuLAK Science News.] 
THE OFFICE OF THE GKEEN PLANT. 
BY J. HOBART EGBERT, M. D., PH. D. 
^Plants may be divided into two general classes, 
(wit : those possessing chlorophyl (green plants) 
those devoid of chlorophyl (fungi, bacteria, 
B.) ; and these two classes are separate and dis- 
^nct, being characterized by certain interesting 
tod important phenomena of life and life-work. 
To the latter class we shall make but a passing 
reference ; still they doubtless subserve an impor- 
tant work in natural life. 
Animals, including man, are either directly or 
indirectly dependent upon the vegetable kingdom 
for sustenance; and, in turn, plants are primarily 
dependent upon the Inorganic world. Many 
plants, however, need organic material for food, 
it being only those plants which possess the green 
coloring matter known as chlorophyl that are able 
to th rive upon inorganic compounds. The essen- 
tial features of life are the same in all living 
things, i. «., in the members of both the animal 
and vegetable kingdoms. Thus plants have or- 
gans for sustaining life in common with animals. 
They take in food and digest and absorb nutrient 
matter ; they respire air, breathing in oxygen and 
exhaling carbonic acid gas; and as a result of 
this life a capacity for doing work is developed, 
a large portion of which is stored up in the plant 
as latent or potential energy, ilanifest energy is, 
however, also produced. Heat is a manifestation 
of energy in plants as well as in animals, and is 
easily demonstrated by adjusting a thermometer 
in some sprouting peas, which, when properly 
arranged, will indicate the amount of heat given 
off. Motion as a manifestation of energy in plants 
is also observed. Thus Oie zoiispores of many of 
the Cryptogamia exhibit ciliary or anid'boid move- 
ments resembling those seen in animalcules ; and 
even among the higher orders of plants quite a 
few exhibit such inherent power of movement, 
either at regular times or on the application of 
external irritation, as might lead one to regard 
them as sentient beings. Diowea muscipula (Ve- 
nus's fly-trap) and Mimosa sensitiva (sensitive 
plant) may be mentioned as examples of this 
class. 
Animals require organic compoimds for food, 
and so do all those plants which do not show a 
green color ; but even here we find a well-marked 
line of distinction between plants and animals. 
Animals require food containing compounds which 
are as complex as the organic proximate princi- 
ples of their own bodies, while this is not essen- 
tially so with plants. Thus .animals must be sup- 
plied with proteids, while plants can make their 
own — since even those plants which have no chlo- 
rophyl can extract the nitrogen and sulphur from 
simpler organic material and build up proteids 
for themselves. The green plant, ho« ever, has a 
greater work to perform, transforming inert, sta- 
ble compounds into complex food stufl's exceed- 
ingly rich in potential energy. IIoW is this ac- 
complished? If a cell of a green plant be exam- 
ined under the microscope it will be seen to have 
somewhat the following arrangement: In the 
first place there is the cell-wall, composed of cel- 
lulose, which surrounds the cell and connects it 
with neighboring cells ; within the cell is an ap- 
parently homogeneous mass, known as proto- 
plasm, — the vital principle of the cell, — and some- 
where in the protoplasm may be detected a nu- 
cleus, while scattered here and there throughouf 
the cell contents the cblorophyl bodies appear as 
green spots. Up^n close inspection small whitish 
specks are to be observed imbedded within the 
chlorophyl; these are starch granules, for it is 
into starch that the inorganic compounds are first 
changed. The reaction may be simply expressed 
thus: 
6CO, -I- 5If,0 = C„II,„05 -f 60, 
carbon dioxide water starcli oxygen 
By this equation it is shown that two stable com- 
pounds, having their molecules completely satis- 
fied with oxygen, are broken up and combined to 
form an euergetic organic compound, while uu- 
comb ined oxygen^is liberated.', ^Thus oxygen is 
given off in a free~state; by;; plants, and may be 
collected and shown to be such by the regular 
tests. Thus energy is developed. But whence 
does it come? Energy, like. matter, is neither 
created nor destroyed, although it may be trans- 
ferred and transformed; hence the plant must 
take it in from without, obtaining it from some 
other form of energy. This potential energy is 
supplied to the plants by the light of the sun, 
whose actinic rays they absorb. The chlorophyl 
and the protoplasm are the machines by which 
this mighty work is wrought, and the media 
through which plants absorb the kinetic energy 
of sunlight and transform it into potential energy, 
which is accumulated during the growth of the 
plant in its tissues and in the food stuffs produced 
by it during its growth. 
Green plants, by virtue of their chlorophyl and 
the light of the sun, absorb from the air and soil 
carbonic acid gas, water, ammonia, and free nitro- 
gen, and convert them into organic compounds 
rich in potential energy and suitable for the nour- 
ishment of all animals. At the same time the 
plant absortjs the carbonic acid gas from the 
atmosphere, it restores to it free oxygen, and the 
necessary constituents of the air are balanced. If 
this were not the case, all available free oxygen 
would soon be consumed, and all life would be- 
come extinct. While oxygen is liberated by 
plants, it should be remembered that they all 
inhale oxygen and exhale carbonic acid gas in 
common with all living things ; but the amount of 
oxygen inspired in the respiration of the plant is 
exceedingly small compared to the amount of car- 
bonic acid gas taken in as food by the plant, and 
the amount of carbonic acid gas given off in expi- 
ration is insignificant compared with the amount 
of free oxygen liberated. 
Sunlight, as before stated, is essential to the re- 
production and action of chlorophyl, and conse- 
quently to the vitality of the green plant. Chlo- 
rophyl is only formed under the influence of light. 
If a seed be pliinted in a dark cellar it will spi'out 
in virtue of a certain amount of food matter stored 
up within it by the parent plant ; but as soon as 
this food is consumed it has no power to create 
more food, and consequently loses its green color, 
becomes stationary in growth, and finally dies. 
A similar degeneration occurs in a developed 
green plant if placed under similar circumstances. 
Green plants, then, by the action of the sun- 
light upon the chlorophyl, transform simple stable 
combinations into complex compounds, whereby 
solar energy is transformed into chemically po- 
tential energy and stored up in vegetable tissues. 
Animals by oxidation decompose, or break up, 
the complex compounds manufactured by plants, 
transforming potential into kinetic or manifest 
energy. Thus there is a constant circulation of 
matter and a constant exchange of energy be- 
tween plants and animals. The energy of ani- 
mals is derived from plants, and all the energy of 
plants arises from the sun. Hence the sun is the 
cause and original source of all energy in natural 
