124 Descriptions of Preparations. 



38. Anterior Segments of Earthworm 



{Limibi'icus Terrestris), 



In number about forty, and including three placed posteriorly to the clitellus ; 

 dissected so as to show the reproductive system, the whole of which, together 

 with the various accessory organs, is contained in or constituted by modifications 

 of the structures of these segments ; as also the portions of the pseud-haemal and 

 the digestive system which are contained in this part of the animal's body. 



The integument having been divided down the middle dorsal 

 line and pinned out on either side, the digestive tract is seen to 

 occupy the middle line of the Preparation, and to have in con- 

 nection with it the vascular system, which is called ^ pseud-haemal/ 

 because though the fluid which it contains is coloured and prob- 

 ably respiratory in function, it is not corpusculated, and therefore 

 not morphologically blood. The digestive tract manifests a very 

 considerable degree of heteronomy, consisting of a pharynx which 

 extends through the first six segments ; an oesophagus which 

 extends through the succeeding ten ; a crop which occupies a large 

 space in the sixteenth and seventeenth; a gizzard which is seen 

 in the seventeenth and eighteenth ; and Anally, the intestine which 

 is laterally sacculated for its first eight segments, and posteriorly 

 to them more evenly cylindriform. The pharynx has a coarsely 

 vUlous exterior, owing partly to the breaking away in the dis- 

 section of the muscular bands by which it was connected with the 

 muscular dissepiments and with the body-walls, and partly to the 

 salivary gland-tissue which composes part, and especially the outer 

 part, of its walls. The oesophagus is of much smaller calibre than 

 either of the two segments of the digestive tube, the pharynx and 

 the crop which it connects. The so-called ^hearts' are in close 

 connection with it in the anterior segments of its course, and the 

 reproductive and certain oesophageal glands are seen at its sides 

 in the middle and posterior. The crop is considerably distended 

 with dark coloured contents, and forms a larger mass than the 

 thicker coated lighter coloured gizzard which comes next behind it. 

 The dorsal pseud-haemal vessel is well seen along the median 

 dorsal line of the crop and intestine, where owing to the con- 

 traction of its muscular walls it has a moniliform appearance. 



