BULLETIN OF THE UNITED STATES FISH COMMISSION. 83 



Three years later, entirely independent of Moudini, the celebrated 

 zoologist, Otto Friedrich iMiiller, published his discovery of the ovary 

 of the eel in the "Proceedings of the Society of Xaturalists," at Berlin.* 



The discovery of Mondini was next specially bronght into prominence 

 through Lazzaro Spallanzani. This renowned investigator, in October, 

 1792, went from Pavia to the lagoons of the Po, near Comacchio, for the 

 sole purpose of there studying the eel question. He remained at 

 Comacchio through the autumn ; he was, however, unable to find any- 

 thing that was new regarding the question, but in the report upon his 

 journey of investigation he entirely threw aside the discovery of Mon- 

 dini, and announced that the ovaries discovered by this authority were 

 simply fatty folds of the lining of the stomach.t 



It was without doubt this absolute negative statement of such a 

 skilled investigator as Spallanzani which for a long time discouraged 

 further investigations on the eel question, and allowed what had al- 

 ready been discovered to be regarded as doubtful, as finally to be for- 

 gotten. So when Professor Rathke, of Konigsberg, in his assiduous 

 labors upon the reproductive organs of fishes, in the year 1824, described 

 the ovaries of the eel as two cuff and collar shaped organs on both 

 sides of the backbone, and in the year 1838 described them as new, he 

 was everywhere in Germany (and to a large extent to the present day) 

 regarded as the disco verer.t The first i^icture of the ovary after that of 

 Mondini, and the first microscopical plate of the egg of the eel 

 Hohnbaum-Hornschuch presented in a dissertation published in 1842 — 

 a paper which should be rightly considered as of great importance in 

 the literature of this question. The questions concerning the ovaries 

 of the eel may be regarded as having been brought to a distinct conclu- 

 sion by Rathke, who, in the j ear 1850, published an article describing 

 a gravid female eel, the first and only gravid specimen which had, up to 

 that time, come into the hands of an investigator. 



O. F. Miiller, and independently from him, discovered the ovaries of the eel. The 

 error, as was discovered by Italian zoologists later than by those of Germany, arose 

 from the fact that the announcement of Miiller's discovery was printed in 1780, while 

 that of Mondini, which was made in 1777, was first printed in 1783. 



*0. F. Miller, Bemiihungen, bei den Intestinal Wurmern 



i Bathke, who first, since Mundini, has in detail described (1824, 1838, and 1850) the 

 ovaries of the eel, is considered by some to have recognized them; but this, however, 

 is not true, the additions made by him to Mundini's description being to a great 

 extent erroneous. It is not true that the transverse leaflets are Avauting in the ovaries 

 of the eel, as he asserts in his last work, contrary to his former description, which was 

 probably based on the law of analogy, and that thereby they are distinguished from 

 those of the salmon and sturgeon. It is not true, what Rathke likewise asserts, that 

 the genital opening of the eel consists of two small canals, for I have invariably only 

 found one, which opens in the urethra. Rathke has >ertainly described the eggs quite 

 exactly, distinguishing the larger whitish ones, having a diameter of about one- 

 fifteenth of a line, and the smaller transparent ones, with the germinal vesicle inside ; 

 but Mundini likewise says : '^innumeras sphwnilas minimus, cequales, pellucidas, divisas 

 tamen, qnoe in centra macidam ostendebant, ecc. vidi,"' thus showing the true nature of the 

 ovaries and the eggs, and contrasting them with the fatty formation and with the 

 ovaries and eggs of other osseous fish." (Syrski.) 



