55 
[ have already shown (p. 13) that Vallisnieri, who gave a 
particular attention to the study of Oestridae, had a presentiment 
about the connection of these flies with the craze of the Bu- 
gonia, but that he was mistaken when he thought that this 
explanation exhausted the subject. It was Réaumur (p. 9), who, 
by breeding Wristalis (his mouche-abeille), and Helophilus (his 
mouche-quépe) from rat-tailed larvae, finally solved the problem. 
But even before Vallisnieri (1661—1730), some authors 
seem to have had an inkling that some of the flies, swarming 
about domestic animals, do not issue from their carcases, but 
from their dejections. I have quoted (p. 48) a passage from the 
dictionary of Calepinus (1559), which contains the words: apes 
ex bovum fimo, sicut crabrones ex equorum, fuci ex mulorum, vespae 
ex asinorum eacrementis.“ The crabrones ex equorwn excrementis 
answers exactly the view which I have just exposed, that the 
horse-born hornet (erabro) of the ancients corresponds to the 
common parasite of the horse, our gad-fly, Gastrophilus equi. 
I believe that my explanation of the imbroglio between the 
horse-born hornet and wasp is the only possible, unless we cut 
the gordian knot by considering the whole of it as a mere 
craze, comparable with the spontaneous generation of a snake 
from the human spinal column (p. 25), but such an extreme course 
is not at all necessary. 
VI. 
The fable by Lessing (compare above, p. 25). 
Die Wespen. 
(Lessing’s Fabeln I, 16) (1). 
Hippos errhimenos sphecon genesis estin, Aelianus de natura 
animalium I, 28. 
Faulniss und Verwesung zerstiérten das stolze Gebiu eines 
kriegerischen Rosses, das unter seinem kithnen Ritter erschossen 
worden. Die Ruinen des einen braucht die allezeit wirksame 
(1) Lessing’s Werke, Stuttgart, Géschen’sche Verlagshandl., 1874, I, p. 146, 
