176 



COLLEGE ZOOLOGY 



amoeboid cells (corpuscles), which corre- 

 spond to white corpuscles in man. Its red 

 color is due to a respiratory pigment termed 

 hemoglobin which is dissolved in the 

 plasma. In vertebrates the hemoglobin is 

 located in the blood corpuscles. 



There are 5 longitudinal blood vessels. 

 These main vessels and their connectives are 

 shown in Fig. 93 and are as follows: (1 "> the 

 dorsal vessel, (2) the ventral (subintes- 



Anterior 



tinal) vessel, (3) the subneural vessel, (4) 

 two lateral neural vessels, (5) five pairs of 

 aortic arches (hearts) in segments 7 to 11, 

 (6) -two lateral esophageal vessels, (7) 

 segmental vessels from the ventral vessel to 

 the nephridia, body wall, and intestine, (8) 

 parietal vessels connecting the dorsal and 

 subneural vessels in the intestinal region, 

 (9) branches to the dorsal vessel from the 

 intestine, and (10) a typhlosolar vessel 



Dorsal vessel- 



Valve- 



Esophagus 



Aortic aich ("heart") 



•Ventral vessel 

 Nerve cord 



Lateral neural vessel 

 Subneural vessel 



Valve between dorsal 

 and t/phlosolor vessels 



Typhlosolar v. 



Typhlosole 

 Intestine 



Afferent 

 intestinal v. 

 Segmental v. 



Nerve cord- 



-Dorsal vessel 



-Dorsal intestinal v. 

 (efferent intestinal) 



Body wall capillaries 



Afferent>^ 



Nephridial vessels 

 Efferent-^ 



Parietal vessel 



Ventral vessel 



(subintestinal) 

 Lateral neural vessel 



Subneural vessel 



Figure 93. Earthworm circulatory system. A, one pair of "hearts" and other vessels. B, a sec- 

 tion to show the structure of a valve. C, a third-dimensional view of two cuts through the 

 earthworm to show the general scheme of the circulation. (A and B modified from Bell; C, after 

 Bell, and a drawing by the Department of Zoology, Kansas State College.) 



