THE ANATOMY OF ONCHOLAIMUS VCILGARIS, BAST. 127 



nuclei are oval, have a nuclear membranej distinct chromatin 

 granules, and nucleolus. At the commencement of the 

 syncytium they measure "OlSG ram. in their greatest diameter, 

 at the termination '0477 mm. There is a narrow, more con- 

 densed, ring of protoplasm round each nucleus. 



The syncytium occupies about one eighth of the length of 

 the ovarian region. It is followed by a column of disc- 

 shaped ova (PI. 8, fig. 19, ov.), which have become separated 

 from it. These ova increase in size as they pass toward the 

 ovarian caecum, and become c^^lindrical I'ather than disc- 

 like in shape. About the middle of the column the ova 

 measures "0484 mm. in diameter. 



The ovarian caecum contains about eight ova. A space is 

 left between the ova and the dorsal wall, through which the 

 ovum which occupies the fundus, and which is the most 

 mature, can pass to reach the oviduct. This mature ovum is 

 richly supplied with yolk-granules (PI. 8, fig. 18, or.). 



The next division of the gonad tube is, in 0. vulgaris, 

 physiologically merely an oviduct, but morphologically it is 

 identical with the subdivision which functions as an uterus and 

 receptaculum seminis in other free Nematodes — e. g. Cylico- 

 laimus magnus and Thoracostoma acuticaudatum. 

 As this division has been described as an uterus by Jagers- 

 kiold, I shall retain the name for the sake of uniformity. 

 The uterus measures 2*5 mm. in length. Its calibre and shape 

 vary according to its contents. It may be distended by a 

 series of large ova or entirely empty. The latter condition is 

 the exception. Generally from four to twelve opaque white 

 ova can be seen in each uterus (text-fig. 2, ov.) lying end 

 to end like a short chain of beads. The uterus then adapts 

 itself, of course, to the shape of the ova. When empty it is 

 collapsed and flat. 



At its commencement a glandular mass, "204 mm. in length, 

 projects into and fills the lumen. This is the shell-gland (text- 

 fig. 2, shg., PI. 8, fig. 19, shg.). Ova, after passing it, are 

 found to have acquired their shells. Its shape is very much 

 that of the ovarian caecum, resembling a conical bullet, the 



