30 GENERATION OF INSECTS 
to shame; being all covered with white spots, they re- 
semble fine enamel work. 
That different generations of flies issued from the same 
dead body was perplexing, and I sought further knowl- 
edge from experiment. To this end, having made ready 
six boxes without covers, I placed in the first, two of the 
snakes described above, in the second, a large pigeon, in 
the third two pounds of veal, in the fourth a large piece 
of horse-flesh, in the fifth, a capon, in the sixth, a 
sheep's heart; and all became wormy in little more than 
twenty-four hours. The worms, five or six days after 
birth, changed as usual to eggs [pupae]. From those in 
the snakes there hatched, after two days, large flies, some 
blue and some purple. The eggs [pupae] in the second 
box, some of which were red and others black, hatched 
out flies; green flies being produced from the red eggs 
[pupae] after eight days, and after fourteen days the 
black eggs [pupae] broke in the place where there was 
no depression, and there escaped from the shell the same 
number of black flies striped with white. Similar flies 
were seen issuing from all the other eggs [pupae] in the 
boxes containing the veal, the capon, the horse-flesh, 
and the sheep's heart; but with this difference, that in 
the sheep's heart, blue and violet flies were produced, as 
well as the black flies striped with white. 
In the meanwhile I had placed in a glass dish some 
skinned river frogs, and having left the dish open, I found 
the next day, on examination, that some small worms 
were occupied in devouring them, while some others 
swam about, at the bottom of the dish, in a watery mat- 
ter that had run out of the frogs. The next day the 
worms had all increased in size and many others had ap- 
peared that also swam below and on top of the water, 
