NOTES AND MEMORANDA. 
277 
the muscles of flight ; this base vibrates and the buzzing is produced. 
But all buzzing ceases if any movement of these organs is rendered 
impossible, by holding the wings tightly pressed together over as 
large a surface as possible, so as to exert a certain strain on their base. 
In whatever manner the wings are held, provided that they are com- 
pletely motionless, the buzzing ceases absolutely, contrary to the 
opinion of Hunter. 
2. By removiug the scaly parts with which the circumference of 
the stigmata is fringed, the buzzing, far from being annulled, as 
Chabrier affirms, is not in any way modified, provided that the opera- 
tion has not weakened the animal sensibly. 
3. The respiratory organs may be injured in different ways, and 
more or less seriously ; solid bodies of considerable size may be 
introduced, without preventing the buzzing or changing its ‘ timbre.’ 
4. If the thoracic stigmata are hermetically closed, as Burmeister 
has done, the buzzing is not in any way extinguished ; it is only 
weakened in proportion to the weakening of the flight itself. 
There are then produced, especially among the Diptera, effects 
which deserve notice. The animal becomes slow and lazy ; it no 
longer willingly flies. If it does so, its ill-sustained flight is not long 
before it stops, then the insect succumbs and no longer gives signs of 
life. 
I once saw an Eristal {E. tenax)^ which having briskly escaped 
from my fingers, towards the window, immediately after the closing 
of the stigmata, fell motionless at my feet, entirely exhausted by a 
flight of a few centimetres. This result does not always follow so 
suddenly, but it never fails to supervene after a few repeated attempts 
at flight. It is easily explained by the complete absorption of the 
provision of oxygen contained in the tracheae of the thorax, in con- 
sequence of the contractions of the muscles of flight. It is a true 
asphyxia. At the expiration of some minutes, however, the fly returns 
to life, owing to the influx of air through the abdomen into the thorax. 
The animal may then again attempt to fly, or at least to walk, but it 
is never long before death finally supervenes. These effects are so 
constant and so easily obtained, that it is really surprising that no 
experimenter has noticed them. 
The causes of the buzzing certainly reside in the wings. It has 
been recognized for a long time that the cutting of these organs, 
effected more or less close to their insertion, exercises a more or less 
marked influence on the buzzing. It becomes thinner and sharper ; 
the timbre itself is considerably modified. It loses the mellowness 
due to the friction of the air on the edges of the wings, and becomes 
in some degree nasal. The timbre perceived under these circum- 
stances recalls that of certain reed instruments, or, better still, that of 
certain electrical contact-breakers, and in no way resembles the sound 
which the passage of air through an orifice may produce. This sound, 
on the contrary, agrees entirely with the repeated beatings of the 
wing-stump against the solid parts which surround it, or of the horny 
pieces which it contains {osselets radicaux of Chabrier) against each 
other. 
