636 NATURAL HISTORY OF AQUATIC ANIMALS. 



Jupiter all children whose paternity was doubtful, were accustomed to say that Jupiter was also 

 progenitor of the Bel. 



" When we bear in mind," writes Jacoby, " the veneration in which Aristotle was held in ancient 

 times, and still more throughout the Middle Ages a period of nearly two thousand years it could 

 not be otherwise than that this wonderful statement should be believed, and that it should be 

 embellished by numerous additional legends and amplifications, many of which have held their 

 own in the popular mind until the present day. There is no animal concerning whose origin and 

 existence there is such a number of false beliefs and ridiculous fables. Some of these may be put 

 aside as fabrications ; others were, probably, more or less true, but all the opinions concerning the 

 propagation of the Eel may be grouped together as errors into three classes : 



"I. The beliefs which, in accordance with the description of Aristotle, account for the origin of 

 the Eel on the basis of its development not from the mud of the earth, but from slimy masses which 

 are found where the Eels rub their bodies against each other. This opinion was advanced by Pliny, 

 by Athenseus, and by Oppian, and in the sixteenth century was again advocated by Rondelet and 

 reiterated by Conrad Gessner. 



"II. Other authorities base their claims upon the occasional discovery of worm-like animals 

 in the intestines of the Eels, which they described, with more or less zealous belief, as the young 

 Eels, claiming that the Eel should be considered as an animal which brought forth its young alive, 

 although Aristotle in his day had pronounced this belief erroneous, and very rightly had stated 

 that these objects were probably intestinal worms. Those who discovered them anew had no 

 hesitation in pronouncing them young Eels which were to be born alive. This opinion was first- 

 brought up in the Middle Ages in the writings of Albertus Magnus, and in the following centuries 

 by the zoologists Leeuwenhoek, Eisner, Redi, and Fahlberg ; even Linnaeus assented to this belief 

 and stated that the Eel was viviparous. It is but natural that unskilled observers, when they 

 open an Eel and find inside of it a greater or smaller number of living creatures with elongated 

 bodies, should be satisfied, without further observation, that these are the young of the Eel. It 

 may be distinctly stated, however, that in all cases where Eels of this sort have been scientifically 

 investigated, they have been found to be intestinal worms. 1 



" III. The last group of errors includes the various suppositions that Eels are born not from 

 Eels, but from other fishes, and even from animals which do not belong at all to the class of fishes. 

 Absurd as this supposition, which in fact was contradicted by Aristotle, may seem, it is found 

 at the present day among the eel-catchers in many parts of the world. 



"On the coast of Germany a fish related to the cod, Zoarces tnviparm, which brings its young 

 living into the world, owes to this circumstance its name Aalmutter, or Eel Mother, and similar 

 names are found on the coast of Scandinavia." 



"In the lagoon of Comacchio," continues Jacoby, "I have again convinced myself of the 

 ineradicable belief among the fishermen that the Eel is born of other fishes; they point to special 

 differences in color, and especially in the common mullet, Mugil cephalus, as the causes of varia- 

 tions in color and form among Eels. It is a very ancient belief, widely prevalent to the present 

 day, that Eels pair with water-snakes. In Sardinia the fishermen cling to the belief that a certain 

 beetle, the so-called water-beetle, Dytiscus Roeselii, is the progenitor of Eels, and they therefore 

 call this ' Mother of Eels.' " 



1 It is very strange that an observer so careful as Dr. Jacoby should denounce in this connection the well- 

 known error of Dr. Eberhard, of Rostock, who mistook a species of Zoarces for an Eel, and described the young, 

 which ho found alive within the body of its mother, as the embryo of the Eel. In Jacoby's essay, p. 24, he states 

 that the animal described by Eborharrt was simply an intestinal worm, an error which will be manifest to all who 

 will take the pains to examine the figure. 



