SCIENCE LETTER FROM PARIS. 548: 
sun or artificially, by means of electricity, is necessary for the production of 
chlorophyll; but M. Boehm has demonstrated by experiments on young pines, 
that unless a certain degree of temperature exists, the influence of the light will 
be next to nugatory. Chlorophyll does not allow all the rays of light to pass 
through its mass indifferently ; some traverse it, but others are retained, absorbed, 
and extinguished. The intense action of sunlight, if prolonged, induces a 
partial decoloration of the leaves, for the chlorophyll cells, which ordinarily 
run together like a string of beads, coalesce and seek the edges of the leaf as if 
for shade from the too powerful solar action. The chlorophyll cells are the seat of 
one of the most important phenomena of vegetation; it is therein where takes 
place the decomposition of carbonic acid; it is by that intermediary that vegeta- 
tion receives and augments its mass of carbonaceous matter. The air is the 
grand source of carbon; for example, the immense regions of sandy soil in the 
southwestern and northern shores of France are barren of carbon, yet pine forests 
flourish there not the less. ‘The carbon comes from the air, similarly as Boussin- 
gault caused plants to grow in sterile sand by merely keeping the roots in contact 
with water. Priestly in 1771 demonstrated, that an atmosphere in which a candle 
became extinguished, enabled a plant to exist, and later, when a second candle 
had been introduced, it burned as usual. The plant had absorbed and appropri- 
ated the carbon of the carbonic acid produced by the combustion of the first 
taper, giving off in return, oxygen to enable the second to burn. It was Housz, 
however, who showed that the leaves decomposed carbonic acid under the 
influence of light. If the living leaves be deprived, pending some days, of the 
action of air, or plunged for a relatively short time into an inert gas, they will 
become incapable to decompose carbonic acid—will perish—they are simply 
suffocated. Some substances, mercury for example, act on the leaves so as to 
render them incapable of decomposing the carbonid acid; they are literally 
paralyzed. 
Cerebral always succeeds articulate rheumatism, and invariably terminates in 
death. When the disease gains the head, the pains in the articulations disappear.. 
Rheumatism of the brain commences by delirium, continues by a succession of 
crises—ending in about twenty-four hours, and fatally—for the rare cases of cure: 
do not count in the struggle. The highest medical authority in France, M. 
Woillez, asserts the affection of cerebral rheumatism can be successfully treated,. 
and without danger to any other existing disease of the heart or lungs—that a 
patient may be suffering from, by means of cold immersions, in a bath reduced 
to sixty-eight degrees Fahr. by means of ice, maintaining the patient therein till _ 
the first symptoms of shivering appear. The bath is to be renewed every three 
hours, and generally three will suffice. It is vitally important to remember that. 
on the first appearance of the symptoms medical aid should be called in, and 
action at once taken; each minute’s delay is a chance removed for success. 
Nothing but immersion must be practiced, as nothing can replace the ice bath,, 
neither local applications of ice, nor lotions, nor wet sheets. These are only 
