62 ALFREt) GIBBS BOURNE. 



front of the large intestine) ; the other network (set of net- 

 works it really is) being in connection with the pharyngeal 

 wall, the septa, and the body-wall. Benham speaks of them 

 as the '^ lateral longitudinal" vessels. I shall show that they 

 are only the much-enlarged representatives in the anterior 

 region of the body of a series of similar vessels which occur, a 

 pair in every segment, in all the remaining portion of the 

 body. There is, in fact, in Megascolex, and I expect in 

 many other earthworms, a vessel on «ach side in every 

 segment — in all except certain anteriorly placed modified 

 segments — a vessel which communicates with capillaries at 

 either extremity, the one network of capillaries being in con- 

 nection with the intestinal wall, and the other with the body- 

 wall, and the blood in circulating either passes from the in- 

 testinal capillaries laden with nutriment to the cutaneous and 

 other capillaries for the nourishment of the tissues and for its 

 own aeration, or is collected in an aerated condition from the 

 cutaneous capillaries to pass to the intestinal capillaries for 

 the absorption of nutritive matters. 



A discussion as to which of these two courses it takes 

 follows the description of the vessels. There is only a single 

 pair of such vessels in the anterior modified region, and it is 

 this pair of vessels which has been called intestino-tegumen- 

 tary vessels by Perrier. I propose to apply the term intestino- 

 tegumentary to the whole series, and to call anterior intestino- 

 tegumentary vessels the large anteriorly placed modified pair, 

 and intestino-tegumentary vessels of such and such a segment 

 those in the posterior region. 



The anterior intestino-tegumentary vessels have relations 

 with the twenty or so most anterior segments, and are, I be- 

 lieve, in connection with the intestino-tegumentary vessels of 

 the following segment, and these again with those that follow, 

 and so on, by means of capillaries or very minute vessels. 

 The relations of the large anterior pair have been dealt with 

 by Perrier, Horst (6), Benham, Beddard, Jaquet, and others.^ 



' These vessels, or at any rate some vessels having somewhat similar 

 relations, have been stated to communicate directly with the dorsal vessel in 



