Vinegar-fly (Drosophila funebris). 299 
gelatinous scum was found to be composed of a bacterium, 
to which he gave the name of “sorbose bacterium ” (“la 
bactérie du sorbose”). The presence of the bacterium 
caused the formation of sorbose (a hexose sugar), 
Bertrand describes an interesting observation in support 
of his opinion that the bacterium is carried to the culture 
by Drosophila flies :— 
“Ayant placé dans une étuve, vers la fin du mois 
d’Avril, un cristallisoir contenant un liquide favorable 
(vin et vinaigre), j’y apercus, apres quelques jours, une 
culture d’aspect caractéristique, développée en _ ligne 
sinueuse & la surface. Une petite mouche du vinaigre, 
venue peut-étre de fort loin, était tombée dans le liquide; 
apres bien des efforts et du chemin parcouru a la nage, 
elle avait fini par mourir; je la retrouvai a l'une des 
extrémités de la ligne sinueuse, au milieu d’une sorte 
d’auréole beaucoup plus large, témoignant de ses dernieres 
luttes contre la mort. I] est manifeste que cette petite 
mouche, née au sein d’une culture antérieure, avait le 
corps recouvert de germes; partout, sur son sillage, elle en 
avait ensemencé le liquide.” 
No doubt Drosophila flies carry other bacteria and 
ferments besides the sorbose bacterium, One organism 
that is commonly carried by them is the ordinary vinegar 
ferment, Mycoderma aceti. When all vinegar was home- 
made Drosophila would thoroughly justify its name of 
vinegar-fly. It would visit the jar containing the sugar, 
treacle, vinegar and water, which were the ordinary 
ingredients employed, and in those cases where no vinegar 
plant had been introduced, it might infect the brew with 
both yeast cells and the vinegar ferment. Flies would 
also lay their eggs in the gelatinous cake that floated upon 
the new vinegar; thus new generations of flies would 
carry away with them the germs that cause fermentation. 
Nowadays, when vinegar is manufactured on a large scale 
and continuously, the presence or absence of Drosophila 
is immaterial. They swarm in vast numbers round 
the vats in vinegar factories, and unless their pre- 
sence becomes troublesome they are tolerated by the 
manufacturer. 
Another interesting example of the carriage of ferments 
by Drosophila flies has been noticed by Mr. 8. H. Davies, 
M.Sce., chemist to the Cocoa Works, York, to whom I am 
indebted for the following :—“ Cases have been observed 
