BULLETIN OF THE UNITED STATES FISH COMMISSION. 



91 



of the ovaries. In tliese organs are likewise found, toward the i^osterior 

 end, the spermatic organs {partes recurrentes), which, however, as is the 

 case with the ovaries, are sometimes wanting. 



The spermatic organs can be distinguished at the first glance from the 

 ovaries of the adult eels and those of the youug eels, not only by their 

 lobular form, but also by their shining glassy appearance, by the surface 

 of the individual lobes, which is smooth and without leaflets, and by the 

 much greater density of the tissue, so that with a pair of pincers one 

 can take ofi' a large portion of the organ, which could not possiblj^ be 

 done svith a more developed ovary whose tissue is as tender as a cob- 

 web, and is composed of small vessels formed of a thin membrane and 

 filled with eggs and fat. 



The fibrous tissue of the spermatic organs is composed of vascular 

 compartments with thicker partitions, inclosing, according to the devel- 

 opment of the organ, granular globules (fig. 7). 



Fig. 6. Three lobes of the right testicle, ivith the deferent canal (enlarged ten times.) 

 a. Lobes, seen from their outer surface. 

 h. Lobe, seen from its inner surface. 



c. Deferent canal. 



d. Anterior part of the same. 



• 



These comjiartments are joined toward the inside and the base of the 

 lobes, which are united to a tube {vas deferens)^ which, cpecal at the com- 

 mencement, runs along the entire length of the abdominal cavity, and 

 opens near the straight intestine {rectum) in a triangular pouch, which 

 likewise contains a vas deferens starting from the caudal part of the 

 spermatic organ. This pouch has its outlet in the general orifice, which 

 opens in the urethra (fig. 8). 



As regards the development of the spermatic organs, I have observed 

 that the lobes of these organs in young eels, measuring not more than 

 200 to 300 millimeters in length, are not yet very distinct, forming two 

 thin ribbons differing but little from ovaries of the female in their aver- 

 age size. In eels measuring about 400 millimeters in length, the testi- 

 cles can easily be distinguished from the ovaries. The former, much 

 straighter, and with tissue, as has been already remarked, much more 

 solid, are provided with a much more developed net-work of vessels; 

 their lobes are very distinct and the deferent canals are usually open, 

 while the ovaries present the appearance- of two continuous ribbons, 



