^§ 137, 138. 



THE ROTATORIA. 



147 



CHAPTERS VI. AND VII, 



CIRCULATOKY AND RESPIRATORY SYSTEMS. 



§ 137. 



As no sanguineous system has yet been found with the Rotatoria, it must 

 be admitted that all the organs are bathed directly by the nutritive liquid 

 which transudes through the intestine. ^^' 



§ 138. 



The vessels observed with the Rotatoria belong probably to the aquiferous 

 system, which, from its structure and limited distribution, must be regarded 

 as of a respiratory nature. In most species, a straight and riband-like organ 

 is seen upon each side of the body, which contains a stiif, tortuous, vasculi- 

 form canal. At the anterior extremity of these two lateral bands, their 

 canals connect with many short lateral vessels which open into the cavity 

 of the body, — their orifices being furnished each with a very active, vibra- 

 tile lobule.^'' 



These lateral orifices have the appearance of pyriforra, or oval cor.pus- 

 cles, in the interior of which, the vibratile lobule, produces the aspect, when 

 its motions are diminished by pressure between plates of glass, of a small, 

 flickering flame. 



The number of these organs varies with the species, and also, it would 

 appear, even with different individuals of the same species. Usually there 



1 The sanguineous vessels which Ehrenberg hSiS 

 frequently described and figured, have not ap- 

 peared as such to Dujardin (Infusoh-es, p. 589), 

 Rymer Jones (Comp. Anat. p. 125), Doyire 

 <Ann. d. Sc. Nat. XVII. 1842, p. 201), and my- 

 self. 



The so-called amiular vessels encircling the body 

 of many species at regular and wide distances, and 

 which, as he himself avows (Die Infusionsthier- 

 ■chen, p. 415), are not connected by longitudinal 

 vessels, are undoubtedly only the transverse sulca- 



tions, or muscles. From their extreme tenuity, it 

 is ditljcult to determine the nature of the other fili- 

 form organs in the body of the Rotatoria, and which 

 Ehrenberg- has also referred to the sanguineous 

 system. }5ut, equally well might they be taken for 

 muscular fasciculi, ligaments or nerves.* 



1 Ehrenberg was the first to point out these 

 vibratile organs, and designated them as the inter- 

 nal gill-like respiratory organs (Abhandl. d. Berl. 

 Akad. 1833, p. 183). 



*[§ 137, note l.] Dalrymple (Phil. Trans. 

 1849, p. 334) has described with Asplanchna 

 Brightwellii what he regards as a peculiar cir- 

 culatory system. It " consists of a double series 

 of transparent filaments (for there is no proof of 

 their being tubes or vessels), arranged, from above 

 downwards, in ciu'ved or semicircular form ; sym- 

 metrical when viewed in front. These filaments, 

 alx)ve and below, are interlaced loop-like ; while 

 another fine filament passes in a straight line, Uke 

 the chord of an arc, uniting the two looped extrem- 

 ities. To this deUcate filament are attached tags, 



or appehdices, whose free extremities are directed 

 towards the interior of the animal, and are affected 

 by a tremulous, apparently spiral motion, like the 

 threads of a screw. This is undoubtedly duo to 

 cilia arranged round these minute appendices. 

 The tags are from eight to twelve, or even twenty, 

 in number, varying in different specimens." He 

 thinks these organs fulfil their function by the cil- 

 iated tags producing currents in the fluid which 

 fills the body of the animal. 



These observations are curious and deserve fur- 

 ther attention. — Ed. 



