Aug. 1, 1899.] Supplement to the " Tropical Agrioultunst." 
147 
Draper demonstrated long ago' that the orange 
rays are the most active in decomposing carbonic 
acid in the leaves. This conclusion was fully 
confirmed by the researches of Sachs, Cailletet, and 
the author, made nearly 30 years ago. The reason 
for this special action of the rays of this part of 
the spectrum were not investigated until the 
Eussian physiologist, Timiriazeff, took up the 
subjecr. He found that the rays which are most 
active in decomposing carbon dioxide are the orange 
and yellow, which are absorbed by chlorophyll 
when the latter is examined with the spectroscope- 
The sume fact has been beautifully dem(mstrated 
by Engelmann- He received a ray of light upon 
a prism so placed under the objective of a micros- 
cope, that on looking through the instrument 
the different rays of the spectrum could be seen. 
He then put a drop of water on a side and added 
a filament of green alga and some putrefactive 
bacteria, which were aerobic. It was observed 
that the bacteria congregated in great numbers on 
that part of the alga lighted by the yellow and 
orange rays. In the green region only a few were 
observed, and these finally collected in the blue 
portion. In other words, the bacteria collected 
in the different rays in numbers approximately 
proportionate to their activity in assisting the 
decomposition of the carbon dioxide by chlorophyll. 
Evidently the rays which pass freely through 
the chlorophyll exert no action. So it happens, as 
shown above, that the extreme red or the green 
rays are without effect on the decomposition of 
carbon dioxide. On the other hand, the orange and 
blue rays are retained and absorbed by the 
chlorophyll, and thus made available for the work 
of decomposing carbon dioxide. The fact that 
orange rays are much more effective than the blue 
is easily explained. The decomposition of the 
carbon dioxide, with the evolution of oxygen, 
requires an expenditure of energy equal to that 
involved in the burning of carbon in oxygen. In 
order, therefore, that the ray.s may be effective for 
reducing carbon dioxide, they must be not only 
readily absorbed but sufficiently warm. The 
orange rays, which are situated at the side of the 
spectrum where the heat rays are concentrated, are 
far more energetic than the blue, because, in 
addition to being readily absorbed, they are 
warmer than the latter. 
The decomposition of carbon dioxide can only be 
brought about by the aid of outside energy. This 
energy is supplied by the sun's rays. Since 
decomposition of carbon dioxide in the chlorophyll 
cells is the source of the organic constituents of 
plants, and since these substances are essential to 
the life of animals, we see that all living beings on 
the earth's surface owe their activity primarily to 
the ^un. 
RINDERPEST. 
D. HuTCHEON, Colonial Veterinaey SuRGtEON, 
Cape Colony. 
As Rinderpest has re-appeared in the Transvaal 
and Bechuanaland several montlis after it wjjs 
believed to have died out in all the states and 
colonies south of the Zambesi, it is of importance 
that the farmers should consider what is the most 
satisfactory method of inoculation to adopt, should 
the disease again invade their herds. When 
writing my annual report for 1897-98, and review- 
ing the character of the work done up to that date, 
and the various methods of inoculation which were 
adopted for the purpose of arresting the spread of 
the plague, and saving as many as possible of the 
cattle exposed to its ravages, I remarked, with 
reference to inoculation, that if we had to com- 
mence the work over again, I had very little doubt 
that, profiting by the information which we had 
gained by painful experience, we could improve 
upon the results which we had previously obtained 
by the adoption of any one of the methods which 
had been tried. For example, in carrying out 
Koch's method of bile inoculation, if the biles were 
extracted ajid selected from affected animals in the 
last stages of collapse, or immediately after death, 
(a system which was carried out in Basutoland 
with such satisfactory results), a stronger and more 
uniform immunity would have been given than 
was frequently obtained. Again, our experience 
clearly indicated that if a larger dose than 10 c.c. 
had been given, or a second inoculation of bile in- 
jected, the immunity conferred by the bile would 
have been very much strengthened and the period 
of protection considerably extended. Further, it 
is Tery probable that if all suitable biles could 
have been kept in an ice chest fer some days before 
being used, infection would not have been conveyed 
to clean herds by bile inoculation, as was undoubt- 
edly done in the majority of instances where fresh 
bile was used ; and we would not now follow 
Koch's bile inoculation by an injection of virulent 
blood. As this is still advocated I will refer to it 
again. I, however, expressed myself as being still 
in favour of using an injection of virulent blood 
after inoculation with glycerinated bile ; beginning 
with very small doses, and repeating the injection 
at short intervals and in increasing doses until a 
decided reaction was obtained, but I do not even 
advocate that now, for reasons which will appear 
later on. 
With respect to the serum method of inocula- 
tion, it is a very interesting fact that although all 
the cattle in a herd are given the disease in a more 
or less modified form by this method of inocula- 
tion, it is comparatively rare that infection is 
carried from such a herd if ordinary precautious 
are taken, and quarantine regulations enforced. 
In the Cape Peninsula, serum inoculation was not 
generally adopted, nor carried out in a systematic 
manner in any locality. Individual herds were 
inoculated at different centres all over che district, 
yet the disease was not spread by that means. On 
the contrary, by the aid of serum inoculation, 
the disease practically disappeared from the Cupe, 
Malmesbury and Tulbagh districts. I expres^ied 
the hope, therefore, that by the adaption of serum 
inoculation, systematic. illy applied, the disease 
could be eradicated iV. m the country. 
Since the above was wiitteti, however, the 
disease has practically died out within the boun- 
daries of the Colony, and until these outbreaks, 
which were reported from the Transvaal the other 
day occurred, we had no information of any cases 
of Rinderpest south of the Zambesi, a condition 
which the most sanguine optimist amongst us 
would hardly have ventured to predict. Such is 
our fortunate poaition, however, and the circum- 
stances being entirely different to what we antici- 
pated al; such an early date, our opinion with 
