«$> 110. THE HELMINTHES. 115 



CHAPTER VI. 



CIRCULATORY SYSTEM. 



§ 110. 



Most of these animals have a vascular system. The circulating liquid 

 is usually wholly colorless, and often contains vesicular or granular cor- 

 puscles, which are difl5cult to perceive from their delicacy and transparency. 

 The circulation is due to the general contractions of the body or of the 

 walls of the vessels. 



In the Acanthocephali, the vessels have no proper walls, but are spread 

 out, as has already been said {^ 106), in the subcutaneous parenchyma. 

 There are two larger, lateral canals, which pass from the neck to the caudal 

 extremity, sending off laterally numerous small canals, which anastomose 

 with each other. A similar net-work is found in the proboscis through its 

 whole length/^' These two canals connect also with the Ie?nnisci, upon 

 each side of the neck. These last, of which there are always two upon tho 

 sides of the proboscis, passing from the neck to the cavity of the body, are 

 usually riband-like, and composed of a finely-granulated parenchyma, 

 which, like the cutaneous one, has a system of vascular canals.^-* 



In most species of Echinorhyjichus, this system consists of a main canal 

 upon the border of the lemniscus, from which are sent off inwardly, nu- 

 merous small branches. These last form the net-work which fills the paren- 

 chyma of the proboscis."' 



In many,^'*' the lemnisci are surrounded by muscular fibres, which, con- 

 verging to the posterior extremity of these organs, form two short muscles, 

 which, in their turn, are blended with those passing obliquely to the pro- 

 boscideal sheath. The point of junction is at a short distance from the 

 place where they are detached from the subcutaneous muscular layer. 

 Each lemniscus is constricted into a narrow neck at its base, which passes 

 into the skin at the base of the proboscis. The junction of the cutaneous 

 with the lemniscian vascular system occurs at this point, as is indicated by 

 the contained liquid passing backwards and forwards between the two from 



1 This vascular system, taken by many Hel- norhynchus claviceps, they are longer than the 

 mintholoffists fjr a digestive canal, has been fig- boily, and lie coiled in its cavity. In Echino- 

 ured by ^Ke.sZrumi (De Helminth Acanthocephalis rhyiichus gibbosus, hystrix. and strumosus^ 

 Tab. II. fig. 10, III. fig. 10, 12, 21), and Barow they are discoid and very short. 

 (Echinorhynchi strumosi Anat. 1S3(5, fig. 1, 8). 'A Echinorhynchus angustatun, haeruca, poly- 

 The movements of the nutritive liquid may be morphus, proteus, and gibbosus. As a wide 

 distinctly seen by placing these animals alive and exception, the principal canal occupies the median 

 undilated as natural under the microscope. One line of the lemniscii, and sends off laterally small 

 will then be quickly convinced that the circulation branches, with Echinorhynchus gigas. Here 

 is due to the general movements of the body. If and there its course is broken by oval, voluminoup, 

 Echinorhynchus is placed in much water, the transparent and apparently vesicular bodies ; see 

 absorption distends not only the body, but the JVestrumb loc. cit. Tab. II. fig. 7. Similar bodies 

 canals of the vascular system are so filled that the in the lemnisci and subcutaneous parenchyma, are 

 subcutaneous parenchyma is swollen, and the found with Echinorhynchus claviceps ; see Mill- 

 gkin is raised here and there into vesicles. ler, Zool. Danica. Tab. LXI. fig. 3. These bodies 



2 With Echinorhynchus angustatus, acus, are, moreover, regular neither as to their number 

 fusiformis, proteus, and polymorphus, the two nor position, and I have not learned their nature. 

 lemnisci have a riband-like form. In Echino- i Echinorhynchus acus, angustatus, fusifor- 

 Thynckus gigas, they are very long ; and in Echi- mis, and proteus. 



