G26 



SYSTEMATIC HISTORY OF THE IXFUSORIA. 



observed. They are found in stagnant water, especially where Conferva) and 

 Oscillatoria) are present. 



The violet-colom\^d supposed digestive glands or cells are, in the opinion 

 of others, simply vesicles coloured by the Oscillator ia on which the animal- 

 cules feed (p. 312). 



This genus and the preceding, Chilodon, are very closely allied. Stein 

 finds the best distinctions between the two in the rounded body with the ex- 

 tremities obtuse and rounded off, in the case of Nassula, and in the flattened, 

 compressed body, with decided ventral and dorsal surfaces and with a lip-like 

 process, in Chilodon. 



NASsrLA elegans (xxiv. 310, 311 



XXVIII. 11-15). — Cylindrical or oval, 

 slightly attemiated in front, extremities 

 very obtuse. It is white or greenish, 

 spotted with violet vesicles. Vacuoles, 

 containing Clilamidomonads or other 

 food, may often be observed ; and from 



of a brownish-green colour, variegated 

 with numerous violet vesicles. The 

 posterior part of the body has a smaU 

 excavation. Ehrenberg says, there are 

 from six to eight groups of vesicles, 

 forming a wide circle round the mouth, 

 filled with a -violet-coloured juice, which 



fifteen to twenty rows of cilia may be i is discharged with the excreta, and ap- 

 seen on one aspect. The animalcule pears like drops of oil, but soon mixes 

 s^^•ims baclvward and forward, turning with and colom's the water. It swims 

 upon its longitudinal axis. The mouth , rapidly, rotating also on itself, but this 

 is easilv perceived by the crn'rents when ouly slowly. Among swinrming clusters 

 indigo is mixed "v\uth the water : it has j of bsciUatorice. 1-96" ; ova 1-4800". It 

 a circlet containing twenty-six little | has been seen in an encysted state. 



wands or teeth, which can voluntarily 

 diverge or converge anteriorly. Four 

 round contractile vesicles, placed in a 

 row, occur on the dorsal surface, and 

 doubtless represent four expansions of a 

 continuous contractile vessel along that 

 region. The violet vesicles mentioned 

 are only accidental (i. e. not necessary) 

 collections of pigment matter, derived 

 from the food (see p. 312). When self- 

 division ensues, the large central nucleus 

 divides (xxiv. 310, 311; the latter is a 

 young one). With Lemnge and Con- 

 "fervse. 1-140" to 1-120". Nassida ele- 

 gans is thus characterized by Cohn : — 

 Elongate with rounded extremities; 

 oesophagus funnel-shaped; no cylinder 

 of teeth present as in N. ornata. Con- 

 tractile vesicles two ; nucleus elliptic, 

 with nucleolus lodged in a fossa at one 

 end. A large mass of violet granides on 

 under surface posteriorly. It resembles 

 but is smaller than Paramecium AiireUa, 

 and has a similar cuticle. With Bursaria 

 trimcateUa and Ophryoglena atra. It is 

 smaller than N. ornata. Its changes of 

 form are remarkable ; often dependent 

 on swallowed joints of Oscillatorice. Cilia 

 very closely disposed. 



N. ornata {N. viridis?, D.) (xxviii. 

 65-71). — Ovate or globular, depressed, 



N. aurea. — Ovate-oblong, nearly cylin- 

 drical, very obtuse at the extremities. 

 Its colour varies from golden yellow to 

 a dark brown. 1-120". 



Stein hints it as probable that this 

 species and N. viridis (Duj.), Chilodon 

 aureus, and Ch. ornatus are merely dif- 

 ferent stages of the same animal. 



N. amhigua (Stein) (xxviii. 2, 3). — 

 Rounded, short oval ; extremities equally 

 rounded. Entire surface covered by cilia 

 in longitudinal rows. The wedge-shaped 

 oral opening surmounts a -\'ery wide pha- 

 rynx (tooth-cylinder, Ehr.) which may 

 be easily isolated. The contractile vesicle 

 acquires a stellate figure during its con- 

 tractions and dilatations, like that of 

 CJiilodon ornatus. The contents are ori- 

 ginally coloiuless, but become tinted 

 green, blue, and red successively, during 

 the process of digestion of the Oscillatoria 

 it feeds upon. It occm-s encysted, in 

 a transparent, resistant, globular cyst. 

 Length 1-240" ; width 1-420". ' 



N. concinna (Perty). — Ovate, hyaline, 

 transparent; covered everywhere -^-ith 

 fine granules having an annular arrange- 

 ment. Dental apparatus particularly de- 

 licate, more evident when dried. Cilia 

 very fine ; movements sluggish ; anal 

 opening at posterior extremity. 1-21G". 



Genus LIOSIPHON (Ehr.).— Turgid; ciliated throughout; frontal ex- 

 tremity advanced beyond the mouth, and not auriculatc. Mouth opens into 

 a tubular membranous pharynx, pro-sided with a cylinder of teeth. 



