16 COMPARATIVE ANATOMY. 



ventral cord containing about twenty-four ganglia, from which 

 delicate nerves radiate on either side. The ganglia are more 

 approximated at both ends than at the middle of the animal. 

 From the foremost, or sub-cesophageal, ganglion pass the nerves 

 to the oral muscles and the cords on either side of the oeso- 

 phagus. These, meeting above, join the super -cesophageal 

 ganglion from which radiate nerves to the ten ocelli and other 

 parts of the head. 



The testes are nine spherical bodies on either side of the 

 nervous cord connected by their ducts with a common canal, or 

 ' vas deferens/ which runs external to them and communicates 

 in front with a receptacle or 'vas deferens.' The two receptacles 

 are connected with the muscular ball from which the penis is 

 continued. The ovaries, smaller than the testes, are situated, 

 one on either side, just behind the 'receptacula seminis,' and 

 are connected by short oviducts with the muscular bag or 

 vagina. 



DIVISION ANNULOIDA. 

 Class II. NEMATELMINTHES. 



27. The generative organs of a male and female Ascaris 

 (Ascaris lumbricoides, L.), taken from the duodenum of a 

 young woman. The male, on the left, is smaller than the 

 female. It the male has been opened longitudinally, and 

 the intestine, a straight tube, is seen passing from the mouth to 

 the anus. It has been pinned somewhat to the left of the 

 specimen. The testis is a long curling tube, very attenuated at 

 its commencement. It gradually becomes thicker, and is dis- 

 posed in numerous coils round the alimentary canal. About 

 three inches from its termination it suddenly dilates into a 

 larger tube or receptacle, which, narrowing again, is continued 

 to the posterior extremity of the animal. Its lowest part, 

 beneath which a slip of blue paper has been placed, admits of 

 protrusion, and is called the penis. 



The female has also been laid open longitudinally. The 

 intestine, like that of the male, is a straight tube, extending 

 the whole length of the animal, but it expands much more 



