OF THE PHILODIX^A. 



703 



end ; the four European species have two spherical alimentaiy glands, and 

 an ovary, with a few large ova ; occasionally these species are \'iviparous. 

 In three of them a contractile vesicle is present. In R. macrurus, near the 

 alimentary canal are two glands. In three species from nine to twelve 

 parallel transverse muscular bands have been observed ; and besides these, 

 in the four European species, styHform tubes emanate fi^om the neck, which 

 in one species are ciliated anteriorly. Two red frontal eyes are met with in 

 the four European forms, and beneath them, in R. vulgaris, two ganglia. 



creature attach itself by the foot, and 

 the rotary apparatus be in motion, a 

 strong cmTent or vortex is produced on 

 each side the wheels, resembling two 

 spirals in the water, which bring the 

 nutritive particles to the mouth, from 

 which some are chosen and the rest flow 

 away. In order to observe this action with 

 effect, finely- divided carmine or indigo 

 must be mixed in the water. The oral 

 apertm-e is placed just beneath the hook- 

 like proboscis, from whence it continues 

 backwards as a long extensible tube, as 

 far as the cesophageal head, which has 

 four muscles and two striated jaws with 

 double teeth (Zygogomphia). From this 

 point a filiform intestinal canal extends 

 posteriorly, forming an oval expansion 

 near its termination at the anus, at the 

 base of the tail-like foot. A thick glan- 

 dular cellidar mass, often yeUo^\dsh or 

 greenish, smTounds the alimentary canal; 

 its use is unknown : anteriorly are two 

 biliary glands. The propagative system 

 is very mteresting : the ovary is a glo- 

 bose glandular mass ; in it four or five 

 ova sometimes so completely develope 

 themselves that the yoimg creep out of 

 their envelopes, extend themselves, and 

 put their wheels in motion while within 

 the ovary ; they sometimes occupy two- 

 thirds the length of the parent. In the 

 ovimi the 3"0img are coiled up in a spiral 

 manner. A contractile vesicle exists, and 

 eleven or twelve parallel transverse bands, 

 probably muscular. The two red frontal 

 eyes, with a ganglion beneath them, in- 

 dicate a neiTous system. These eyes are 

 cells fiUed with a granular pigment, and 

 sometimes separate abnormally into se- 

 veral ; Leydig affirms that they contain 

 a refracting body. (xxxv. 476, a fidl- 

 grown animal extended, and supposed 

 to be attached to a fixed body — the 

 currents about the trochal disc as dis- 

 played when indigo is put in the water ; 

 477, an imder view, the wheels with- 

 appear to be present. It has two kinds of | drawn, and body contracted ; 478, an 

 locomotion, — one by alternately attach- ! extended Rotifer, wheels withdrawn ; 

 ing the mouth and foot, and, as it were, 479, 480, upper portions more highly 

 stepping along ; the other by swimming, I mag-nified, after submission to different 

 through the rotary apparatus. If the i degi-ees of pressiu'e between the plates 



Rotifer vulgaris ( VorticcUa rotatoria, 

 M.) (xxxv. 476-480). — Body fusiform, 

 white, gradually attenuated towards the 

 foot; eyes round. This creature, which 

 was discovered by Leeuwenhoek, was 

 described and illustrated in the Micro- 

 scopic Cabinet some years ago, prior ,to 

 the appearance of Ehrenberg's observa- 

 tions. " It has the power of contracting 

 or extending the length of the body in 

 the following remarkable manner : — 

 When the creature is about to shorten 

 itself, transverse folds or joints are ob- 

 servable, which do not appear to be con- 

 fined in number or situation ; the in- 

 teguments, when a joint is produced, 

 are dra^^^l within the parts above, and 

 slide out like the tubes of a telescope, 

 when the joints disappear. It is this 

 power that enables it to assume the 

 fomi of a sphere, the head and tail being 

 drawn within the body." Anteriorly it 

 has a proboscis-lilie process, with a cili- 

 ated extremity, and a soft hook, near 

 which are two dark red poiuts. The body 

 terminates posteriorly in a moderately 

 long tail-like foot, having six processes 

 disposed in pairs; two wreaths of cilia (the 

 wheels), voluntarily moveable, are placed 

 upon short thick arms (pedicled), which 

 can be drawn in and out at pleasure ; 

 these MTeaths serve for s-^dimning and 

 purveying, the food approaching the 

 mouth through the cmTents produced in 

 the water by the cilia. On the dorsal 

 surface is a stj^ifonn horn (speculum 

 collar e, M.), at the end of which Leydig 

 detected retractile cilia. During vibra- 

 tion the neck has a circular fold, which 

 appears on each margin in a front view 

 like a lateral style. Four longitudinal 

 muscles, two anterior and two posterior, 

 are seen ; laterally also two, club-shaped, 

 for moving the foot, and two belonging 

 to the rotary organ. Sometimes, says 

 Ehrenberg, fom- anterior longitudinal 

 muscles and a dorsal and ventral muscle 



