some worms, and some kinds of bees and wasps are, either of dew or out of the corruption of the earth, seems to be made probable by the barnacles and young goslings bred by the sun's heat and the rotten planks of an old ship, and hatched of trees.'
The passing of Aristotelianism and the revival of the sciences, in the sixteenth century, was the occasion of this renewed interest in eels. It was not, however, until the eighteenth century that sex in eels was definitely recognized. Sancassini, a surgeon of Comacchio, in Italy, visited the eel fisheries at that famous place of eels, and chancing to be struck with the appearance of a large one, his professional instinct led him to use his knife. The result caused him to send it to Vallisneri at the University of Padua, who recognized with enthusiasm the true ova and forthwith communicated this fact to the Academy at Bologna. Vallisneri has since been appropriately honored by the bestowal of his name upon a water plant well known to all—eel-grass. But the immediate effect of his announcement was an eel controversy. Eels became the burning topic of the hour among the professors, the best-known names of the time are associated with the discussion, and Bologna became the storm-center of the eel question. Another specimen similar to the first increased the agitation. But Valsalva, of anatomical fame, showed that there were certain appearances in almost any fat and well-favored eel that strongly simulated what Vallisneri had described, and in brief, hinted that the alleged eggs were globules of uninteresting adipose. . An enthusiast offered a reward for an eel that should contain undoubted eggs. Of course he got it. His joy was short-lived, for a critical inspection showed that mercenary considerations had led the fisherman to fill the specimen with foreign eggs. This irreverence, and at this juncture, disturbed the seriousness of the situation and the eel question slumbered for over half a century. Then, again from Comacchio—whence emanated many of the errors and the final truth—another eel falling into initiated hands marked the crisis in the eel question. Among these privileged ones was the famous Galvani, and in grave council assembled, he agreed with the others that it was the counterpart of Vallisneri 's historic eel of seventy years before, and was a precious specimen and must be sent to the naturalist Mondini. And Mondini, in a publication which is classical, first described in accurate terms the female eel, and lifted the eel question out of the uncertain field of speculation to a basis of solid fact.
Not immediately, however. Spallanzani a few years after visited the Comacchio region for the sole purpose of studying eels and reported a negative to Mondini 's observations, which accordingly suffered a nearly total eclipse lasting many years. In 1850 Rathke was able to describe an eel in full roe, the first that ever came into the