512 



SYSTEMATIC HISTORY OF THE INFUSORIA. 



The integument of Disehnis is non-resistant, diaphanous, breaks up after 

 death by diffluence, and is sometimes filled with a green substance. Like 

 plants, these beings are sensitive to light, fix themselves to the lightest part of 

 the containing vessel, and disengage oxygen when exposed to the sun's rays. 

 In the green substance are seen granular masses, a disk with an expanded 

 border, and a red speck. The motor filaments proceed from the same opening 

 of the integument, and often form a diaphanous lobe projecting from the 

 opening. The red colour oftentimes seen in the water of the Mediterranean 

 appears due to Infusoria of this genus. 



DiSELMis viridis = Chlamydomonas 

 pulviscidus (Ehr.) (xix. 16). 



D. marina. — Nearly globular, obtuse 

 and rounded in front, granular within. 

 1-1050". 



This species is larger than D. viridis, 

 more globular, and apparently deficient 

 of the red speck. In stagnant sea-water 

 of a green colour. 



D. angusta. — Pyriform, oblong, ap- 

 pearing to be plaited and tubercular 



inside, sometimes with an indistinct red 

 speck. 1-2600" to 1-1850". 



D. Dunalii. — Oval or oblong, often 

 constricted about the middle ; colom-less 

 when very young, then green, afterwards 

 red ; with 2 flagellifonn filaments longer 

 than the body, seated on a projecting and 

 retractile anterior lobe. Interior occupied 

 by coloured globides. Discovered by 

 M. Joly to be the chief cause of the red 

 coloiu" of the water of the Mediterranean. 



Genus ANISONEMA (D.) (XIX. 8; XXYI. 8).— Colourless, oblong, more 

 or less compressed, having a resistant envelope giving exit by an opening to 

 two filaments, one dii'ected forwards and flageUiform, the other trailing back- 

 wards and retractile ; movement slow. 



*' In other genera, as in Hetei^omita, two similar filaments exist ; but the 

 present genus is known by its non- contractile resistant integument, which is 

 often met with empty and transparent. It may be that the Bodo grandis 

 (Ehr.) is allied to this genus as weU as to Heteromita.'^ 



trailing : he supposes it in the act of 

 fission ; but his figure does not show it. 



A. sidcata (xxvi. 8). — Oval, depressed, 

 with 4 to 5 longitudinal furrows, and an 



Anisonema Acinus (xix. 8). — Oblong, 

 depressed, rounded posteriorly, and nar- 

 rower in front, like the seed of an apple, 

 with an opening close to the apex; 

 colourless and transparent, except a few 

 vesicles, mostly green, but occasionally 

 red ; movement in a straight line for- 

 wards. 1-1300" to 1-850". In pond- 



oblique notch in front, from which the 

 two filaments proceed ; moYement vacil- 

 lating, circular. Perty has seen it divide 

 longitudinally. 1-1300". The projecting 



water. This species = Bodo grandis (?) filament is t£ree times, and the floating 

 (Ehr.). Perty gives afigm-eofan organ- j one about twice as long as the body; 

 ism he identifies with this species, hav- j in this, however, says Perty, there is no 

 ing four filaments anteriorly and none \ constancy. 



Genus PL(EOTIA(D.) (XXYI. 10, a, 6).— Diaphanous, having several ribs 

 or longitudinal ridges along the middle, and a circular translucent margin, giving 

 the whole a navicular fonn ; two locomotive filaments proceed from one end. 



This distinct fonn might be mistaken for one of the Bacillaria, were not 

 the filaments clearly visible. The characters of the filaments are similar to 

 those of Anisonema — one extending forwards with an undulatory movement, 

 the other trailing and capable of suddenly arresting the movement of the 

 body by its adhesion and power of retraction. 



Plceotia vitrea (xxvi. 10 a, h). — Hy- I 1-130" ; movement slow. In sea-water 

 aline, with 3 to 4 longitudinal salient I kept for two months, 

 lines at the centre, and some granules. I 



Genus OXYERHIS (D.) (XXYI. 9 a, 6). — Ovoid, oblong, obUquely 

 notched in front, and prolonged into a point ; several flagelliform filaments 

 proceed laterally from the bottom of the fissure. 



