THE EARTHWORM. 51 



PLATE XII. 



THE EAETHWORM. THB ORGANS OF CIRCULATION, BEPKODUCTION AND LOCOMOTION. 

 THE NERVOUS SYSTEM. THE LAYERS OF THE BODY-WALL, ETC. 



FIG. I. -The so-called hearts, and the great blood-vessels of the anterior twelve 

 segments, seen from the left side. x 2|. 



Dissections of the blood system of this .animal are best performed on specimens some 

 six to eight hours dead. 



FIG. II. The vessels of three postgenital segments, seen from the left side. 



The excretory vessels are shown in the posterior one, all except the excretory vessels 

 in the middle one, and the circular commissural vessel iu the anterior one. 



In order to see the lateral-intestinal trunks, i.L, the so-called hepatic tissue must be 

 carefully scraped away. 



The subintestinal vessel, i.s 1 ., Figs. II. and V., is very obvious on the under surface of 

 the gizzard, the walls of which are white. x 6. 



FIG. III.- A drop of the perivisceral lymph fluid, examined fresh. 



The nuclei respond most readily to the action of 1 p.c. acetic acid and magenta. D. 3. 



FIG. IV. A drop of the red blood fluid, drawn from one of the so-called hearts with 

 a pipette. F. 3. 



FIG. V. Entire section across the middle of the body. 

 Constructed from a number of sections and dissections. 

 The excretory organs are diagrammatic, x 6. 



FIG. VI.; The portion a-b of the same, highly magnified, to show the order of suc- 

 cession of the layers of the body-wall and of that of the alimentary canal ; also the setae, 

 with their sheaths, muscles, etc. D. 2. 



The excretory organ is here disregarded. 



Mojsisovics (50) has described and figured an epitheloid blood-plexus for the clitellum. 



FIG. VII. The anterior portion of the nervous system, seen from above. 

 The pharynx was displaced, and the left circumoesophageal commissure is supposed to 

 be seen through it. * 31. 



FIG. VIII. A portion of Fig. VI., being a thin section of the nerve ganglion with 

 its muscular sheath, etc. 



The nerve-cells here figured are diffused along the entire length of the nervous axis. 

 [Compare Claparede (42), Plate XL VII., Fig. VI.] D. 3. 



