644 



NATUEAL HISTOEY OF AQUATIC ANIMALS. 



toward the posterior end, the spermatic organs {partes recurrentes), -whicli, 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 onlj' by their lobular form, but also by their 



shining, glassy appearance, by the surface of the individual 



I ulillll 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 oft' a large portion of the organ, which could not 



possibly be done with a more developed ovary whose tissue 



I'/illi " ^** ^® 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, 



J according to the development of the organ, granular 



globules (Fig. 7). 



These compartments are joined toward the inside and 

 J tlie base of the lobes, which are united to a tube {vas deferens), 



which, csecal 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 

 oriflcCj which opens in the urethra (Fig. 8). 

 J As regards the development of the spermatic organs, I 



PM' 



Fig. D.~Male Eel {natural size), 

 a. Eiglit testicle. 

 6. Left testicle. 



c. Rig'bt accessory part. 



d. Left accessory part. 



e. Dividing membrane. 

 /. Deferent canal. 

 a. Seminal pouch, 

 ft. Anal depression. 

 i Urinary bladder, covered to a great extent 



bv the seminal pouch. 

 k. Fat on the right side. 

 k'. Similar fat covering the stomach. 

 I. Fat on the left side, 

 m.. Stomach. 

 n. Pylorus. 

 0. Liver, turned up to show the inner surface 



8?onS *** *^^ <fi3ophagu8 and the ^els measuring about 400 millimetersin length, the testicles 

 q!^q. Pe'^i'o^rai'fins. cau easily bc 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 5 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 

 germinative vesicles. 



Fig. 6. — Three lobes of the right testicle, with the deferent canal {enlarged ten Umes), 



a. Lobes, seen from their outer surface. 



b. Lobe, seen from its inner surface. 



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 



