644 



NATURAL HISTOEY OF AQUATIC ANIMALS. 



A 



toward the posterior end, the spermatic organs (paries 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 

 young 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 off a large portion of the organ, which could not 

 possibly be done with a more developed ovary whose tissue 

 is as tender as a cobweb, 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 development of the organ, granular 

 globules (Fig. 7). 



These compartments are joined toward the inside and 

 the base of the lobes, which are united to a tube (vas deferens), 

 which, cajcal at the commencement, runs along the entire 

 length of the abdominal cavity, and opens near the straight 

 intestine (rectum) in a triangular pouch, which likewise con- 

 tains 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 



I e 





Flo. 5.- Jfofe Eel (naturalize). 

 a. Ubl.t testicle. 

 6. I.- li tent id . 

 e. Right IHT.-M-.OIV part, 

 d. l.-ft a<-o-HHt y part. 

 . Dividing membrane. 

 /. Df*n>nt ranal. 



. Seminul pouch. 

 . Anal ilrpn-HMion. 

 i t"riniry bladder, covered to a great extant 



by th" aimiinal poncd. 

 k Fat <m th \\v\it aide. 

 k . Simil ir fat . nv.-i um the stomach. 

 1. Fat on the left aide. 

 m. Stnti nrh. 

 n. I'yiornfl. 

 v I.i\ i-i . turned up to show the inner Biirface 



FIG. 6. Three lobet of the right teiticle, mth the deferent canal (enlarged ten times). 



a. Lobes, Been from their outer surface. 



b. Lobe, seen from HH inner aurfoce. 



c. Deferent canal. 



d. Anterior part of the same. 



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 average size. In 



*" the <E ' opl "' 1!U8 aml the Eels measuring about 400 millimetersiu length, the testicles 

 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, 

 have a more delicate tissue, and an almost mucous appearance, and contain the eggs with the 

 geruiinative vesicles. 



p. Gull-bladder. 

 9, 9. Pectoral fins. 



