468 EEPOET OF COMMISSIONER OF FISH AND FISHEEIES. [6] 



fate awaited the discovery of Mondini at the hands of Lazzaro Spallan- 

 zaui. This famous naturalist, in October, 1792, undertook a journey 

 from Pavia to the Po lagoons, near Comacchio, for the sole purpose of 

 studying the eel question in that locality. He spent the greater part of 

 the autumn in Comacchio, but did not discover anything new, whilst in 

 the published description of his journey * he entirely rejected Mondini's 

 discovery, and maintained that the ovaria which Mondini had described 

 were in reality nothing but the unusually fat folds of the diaphragm. 

 It is probably this absolutely negative result of the investigations made 

 by so famous a naturalist as Spallanzani which deterred others for some 

 time from any further investigations of the eel question, and which 

 made all that had been so far discovered appear doubtful and fall into 

 oblivion. When, therefore, Professor Rathke, of Konigsberg, in his 

 large work on the generative organs of fish, 1824, t described the ovaria 

 of the eel as two organs resembling frills, extending along both sides 

 of the backbone, and described them a second time| in an article in 

 " Wiegmann's Archiv fiir Naturgesekichte," 1838, he was generally in 

 Germany, even to the present day, considered as the discoverer of the 

 ovaria of the eel. The first drawing of the ovaria after Mondini, and 

 the first microscopic drawing of the eggs of the eel, were given by 

 Hohnbaum-Hornschuch in a dissertation published in 1812,§ which will 

 always occupy a prominent place in the literature of the eel question. 

 The question regarding the ovaria of the eel was definitely settled by 

 Rathke, who, in 1850, published an article in " Midler's Archiv" on a 

 pregnant female eel examined by him, the first and only specimen of a 

 1) regnant eel which so far had been seen by a naturalist. || 



It will be proper to give in this place a short description of the ovaria 

 of the eel. If an eel be opened along its lower side from the breast to a 

 point behind the anus, there is seen besides the entrails and stomach, 

 and underneath the back part of the liver, the long swimming-bladder, 

 growing narrower toward both ends, and extending on the one side as 

 far as the diaphragm, and on the other a little distance beyond the anal 

 opening. Along both sides of the swim-bladder there extends a white or 

 yellowish band, tolerably broad and shaped exactly like a frill, whose 

 inner edge is attached to the swim-bladder by a narrow skin, a duplicature 

 of the inner skin of the abdomen, but whose other edge hangs down free 

 in the abdominal cavity. Each of these frill-like bands extends forward 



* Lazzaro Spallanzani: "Opusculi due sopra le anguille, dove singolarraente si 

 ragiona di quelle che si pescano nello valli di ComaccMo." Opere. (Milan edition, 182G. ) 

 Vol. iii, p. 518. 



t "Neueste Schriften der Naturforschenden Gesellschaft zu Danzig," vol. i, part 3, 

 Halle, 1824. " Ueber den Darmkanal und die Erzeugungsorgane der Fische," von Dr. 

 Heiurich Eathke, p. 122. 



t Wiegmann's Archiv, 1838, i, p. 299. 



^'"De Anguillaruni sexu ac generatione." Inaugural dissertation by Eeinhold 

 Hohnbaum-Hornschuch. Greifswald, 1842. 



I! Miiller's Archiv, 1850, p. 203. 



