428 GENEEAL HISTORY OF THE INFUSORIA. 



the surface to another, in currents not very distinct or persistent, and in no 

 definite direction. He has seen them running in lines down the tail, and 

 collecting in groups. This flowing movement occurs chiefly during the con- 

 tractions and relaxations of the entire animal. He thinks it probable that 

 these granules are connected with the nutrition of the animal, and analogous 

 to the free floating corpuscles of the Tardigrada, described by M. Doyere." 



In his recent paper (Mliller's Archiv, 1857, p. 404), Leydig notes that 

 when individuals of Hydatina senta have been plentifully fed with Euglejia 

 viridis, the fluid (blood) which fills their abdominal cavity, contains numerous 

 clear globules, or blood-corpuscles, of a roundish form and unequal size. We 

 would rather compare these corpuscles to those seen in chyle during the 

 process of digestion, as more strictly homologous with them than with blood- 

 disks. Although no true vascular system is discoverable in the Rotatoria, 

 there is, nevertheless, a tubular apparatus readily seen in most animals of the 

 class (XXXYI. 6 a a, 9 m ; XXXVII. 29 d, 32 ef; XXXVIII. 5 d d, 25 ef, 

 2Q eil, 27 g). It has the form of an apparent band, extends upwards from 

 the cloaca, or near to it, on each side of the body ; and within this a cord or 

 vessel is visible, more or less coiled or convoluted in its com^se, from which 

 small vibrating organs, often pear-shaped, and likened by Ehrenberg to 

 written notes of music, project towards the cavity of the body. These vessels 

 may possibly communicate by one or more transverse vessels running across 

 the neck of the animal ; whilst below, they end either in a vesicle endowed 

 with an active power of contractility or immediately in the cloaca itself. 



Xow it happens that the mechanism of this organization, as well as its 

 fimctions and relations to the other parts of the body, have been so variously 

 described by different waiters, that it is difficult to draw up any satisfactory 

 general account of it ; we shall therefore be compelled chiefly to conflne 

 ourselves to the reproduction of the several statements as presented by their 

 authors respecting the side bands and the contractile vesicle. Ehrenberg 

 adopted the curious notion that they were parts of the sexual organization. 

 The side bands with their coiled canal he represented to be the testes, and 

 the contractile vesicle a sperm -sac (seminal vesicle). The inconsistency of 

 this notion with all oiu' knowledge of animal structure and fimctions, has 

 struck every observer. To adduce but one coimterargument : — the constant 

 discharge of spermatic fluid in a profuse quantity, and in no relation with the 

 number of eggs contained within the ovaiy, is an idea which is per se at vari- 

 ance with all analogy, and directly opposed by the fact that the apparatus is 

 in full activity even when the embryo is still unhatched mthin the body of 

 its parent, — and entirely negatived, at least in several instances, by the disco- 

 very of distinct male beings. 



Again, Ehrenberg called the tremulous tags (XXXVIII. 26 e) gills or gill- 

 like organs, and therein recognizes them as parts of a respiratory system. He 

 thus refers to them : — " Oval, tremulous bodies are in some species observed 

 attached to a free filament-like tube generally placed longitudinally mthin 

 the body ; in some instances they are attached to the two sexual glands {i. e. 

 the side bands), as in Hydatina. Their function is respiratory, and they are 

 analogous to gills ; the tremulous motion observable is that of the laminae 

 composing them. The reception of water within the body for these gills to 

 act upon, is provided for by one or more openings at the anterior part of the 

 body, or in some species by spur-like processes or tubes (siphons)." 



The erroneous belief that the siphon-like antennae (XXXVII. 17 d; 

 XXXVIII. 27 e) and the cuticular fossae were channels for the admission of 

 water into the body was countenanced by Siebold, who explained the respi- 

 ratory act to consist in the entrance of water, by the supposed apertures, from 



