112 ANIMAL PARASITES. 



enlarged and clubbed, and the first commencement of the so- 

 called ova collect in the lateral offshoots, which at first appear to 

 stand more closely in the upper than in the lower half of the 

 segment. From the 500th segment, the lateral shoots exhibit 

 a tendency to give off smaller shoots or excrescences towards the 

 sides, but these always appear to be larger and more numerous 

 in the upper half of the segment, and never reach directly to the 

 main stem. From the 600th segment is seen one-shelled, clear 

 ova, which move readily in the offshoots of the uterus after the 

 preparation has been treated with acetic acid. From the 625th 

 Ave find two-shelled ova, which constantly become thicker and 

 darker coloured, until in the 650 — 700th segments they nearly 

 resemble the mature ova, although still mixed with an abundance 

 of immature ova, and then exhibit the little embryo with its 

 six booklets. 



The structure of the generative organs is as follows : Male 

 organs. — The penis is sickle-shaped, light yellow, smooth, and 

 perforated, so that the outer skin of the penis is seen to turn 

 inwards at its apex; it is about - 122 ///= 0-2?6 millim. in length, 

 0-035 ,,, = 0-071 millim. in breadth behind and 0017"' = 0-039 

 millim. in front. When retracted, it is received by a peculiar 

 bell-shaped organ (a sort of prcepuce), which is O-lTS^'^O-SOo 

 millim. in length, and from the hinder end of which springs a 

 strong, blackish-brown seminal cord, which takes a tortuous course, 

 turning at a right angle towards the uterus, and running nearly 

 to this, in which it forms convolutions of 0-014'" = 0*031 millim. 

 in breadth. I have not yet been able to obtain a testis and 

 spermatozoa, such as Wundt states he has seen and figured. 



Female organs. — The vagina lies on the side of the sac of the 

 penis, which is turned towards the hinder end of the worm, and 

 opens into this near the penis with a funnel-shaped aperture, 

 0-028'" = 0-063 millim. in breadth. At first it runs parallel to 

 the seminal cord, but quits it about the middle of its course, and 

 then bends in sharp curves towards the main stem of the uterus, 

 into which it opens with a small swelling. The vagina appears 

 to be an inward prolongation of the chitinous epidermis. Its 

 lumen measures - 007'""= 0-015 millim., and its diameter is there- 

 fore only about half that of the individual ova. This diameter 

 can hardly be so much increased by the abbreviation of the 

 sheath, as to render it equal to that of the ova, so that we might 

 suppose that the eggs could pass out through this vagina from an 



