NOTES AND MEMORANDA. 
279 
putable that the grave sound always accompanies the great vibrations 
of the wings, which serve for the translation of the insect. It is easily 
seen that this sound commences as soon as the wings begin to move, 
and that if the wings be cut off it disappears entirely. The sharp 
sound is never, on the contrary, produced during flight ; it is only 
observed apart from the great vibrations of the wings when the insect 
alights, or when it is held so as to hinder its movement, and in that 
case the wing is seen to be animated by a rapid trembling. It is also 
produced when the wings are entirely taken away. From these two 
remarks we may draw the conclusion that the grave sound belongs 
properly to the wings, that it is caused by their movements of great 
amplitude. There is here no difficulty. As to the sharp sound, it is 
certainly not produced by the wings, since it survives the absence of 
these. Yet the wings participate in it and undergo a particular trem- 
bling during the production of this sound. To discover the cause it is 
necessary to go back to the mechanism of the movement of the wing. 
It is known that among nearly all insects the muscles which serve for 
flight are not inserted in the wing itself, but in the parts of the thorax 
which support it, and that it is the movement of these which acts on 
the wing and makes it vibrate. The form of the thorax changes with 
each movement of the wing under the influence of the contraction of the 
thoracic muscles. The muscular masses intended for flight being very 
powerful, this vibratory movement of the thorax is very intense, as may 
be proved by holding one of these insects between the fingers. But as 
the vibrations are repeated two or three hundred times per second, 
they give rise to a musical sound, which is the sharp note. In fact, 
the air which surrounds the thorax is set in vibration by that directly, 
and without the wing taking part in it. There are then two simulta- 
neous sounds, one produced by the vibration of the wings and the 
other by the thoracic vibration, the latter twice as rapid as the former, 
and therefore an octave. This is why in flight only a single grave 
sound is heard. When the thorax moves alone, a sharp sound is 
produced. This, M. de Bellesme believes, is the only explanation 
that can be given of the mode of production of the two sounds which 
constitute buzzing.” * 
The Septicity of Putrefied Blood . — The following note was pre- 
sented to the French Academy in July by M. V. Feltz : — “ I showed 
experimentally in 1875 that putrefied septic blood subjected for 
several days to the contact (or passage) of pure oxygen seems to 
become less poisonous, and that it differs from the initial blood by a 
diminution of the movements of the vibrions. I also established in 
1877 that pure oxygen compressed at a high tension during thirty and 
fifty days destroyed the oscillating rods and the vibrions of putrefied 
blood, Wt that it had no effect on the corpuscular germs or conoidal 
spores, which explains the power of the septicity. I have had the 
good fortune to agree on this point with M. Pasteur, who expresses 
himself thus in his ‘ Theory of Germs — 
* Apparently a summary of a paper read before the French Association for 
the Advancement of the Sciences, in August. 
