542 



SYSTEMATIC HISTORY OF THE mrrSOHIA. 



nature, ?*. e. a nucleus. Longitudinal self-division has been observed in E. 

 Acus, and the commencement of it in E. sanguinea (XVIII. 37-39). Close to 

 the red point a supposed nervous ganglion or eye-speck is visible in E. longi- 

 cauda (XVIII. 44), such as is seen in AmhlyopJiis. The genus Euglena of 

 Ehrenberg, saysDujardin, contains some species of a compressed leaf-like form, 

 and quite deficient of contractility, which require to be placed in the genus 

 Phacus of the family Thecamonadina. 



Euglena sanguinea {Cercaria viridis, 

 M.) (x\^n. 37-39). — Extensible, of an 

 oblong-cylindrical or spindle-shaped 

 form, with head greatly rounded ; tail 

 short, conical, and somewhat pointed. 

 Flabelluni longer than the body in its 

 extended condition. When yoimg, they 

 are green, but when fiill-gTown, of a 

 blood-red colour; and specimens are 

 frequently foimd variegated red and 

 green. The motion of this multiform 

 animalcule is generally slow ; and it 

 sometimes revolves upon its longitudinal 

 axis in swimming. The thread-like fila- 

 ment, which is a prolongation of the 

 upper lip, and rather longer than the 

 body, is so delicate as to require consi- 

 derable care in investigating it, and, 

 being reti'actile, wiU often elude obser- 

 vation. A little colouring matter in the 

 water will exhibit this organ in active 

 operation ; and it may be distinctly seen 

 in a single animalcule in a dried state, 

 upon a plate of clear glass. The double 

 appearance of the organ in this species 

 has been before noticed. Ehrenberg 

 conjectured that the miracle in Eg>q)t, 

 recorded by the great lawgiver of the 

 Jews, of turning the water into blood, 

 might have been effected by the agency 

 of these creatures, or by the Astasia 

 hmnatodes. In stagnant water, often in 

 great abundance on the surface. 1-300" 

 to 1-210". This is in all probability a 

 mere variety of E. viridis ; the red 

 colour is not a specific distinction, but 

 only a sign of maturity. 



E. hyalina. — Extensible in a spindle- 

 shaped manner; head attenuated, blunted 

 at the extremity, and two-lipped ; tail 

 short, and somewhat pointed; 001010* 

 transparent and whitish ; rare. 1-280". 

 Perty asserts that it is only a variety of 

 E. viridis. 



E. dcses (Encheli/s deses, M.). — Extensi- 

 ble, cylindrical, abruptly rounded at the 

 head, and slightly bi-lipped. Tail very 

 short and pointed ; colour gi'een ; motion 

 a winding and sluggish creeping, never 

 swimming. Filament very long and fine. 

 Amongst Lemnte. 1-240" to 1-760". 



E. viridis {Cercaria viridis, M.) (xviii. 

 40). — Extensible in a spindle-shaped 



manner; head attenuated and short. 

 Tail short, and cone-shaped, not cleft; 

 colour ^Teen, excepting the two ex- 

 tremities, which are colomless. The 

 double-pointed tail represented by Leeu- 

 wenhoek and others does not exist. 

 When the creatm^e is young, its eye- 

 speck is imperceptible or very pale, 

 and it may readily be mistaken for 

 Astasia viridis or 3Ionas deses. When 

 dried on glass, the speck seldom retains 

 its colour more than a week; but the 

 filament may be well examined and pre- 

 served when so treated. Filament twice 

 the length of the body, which differs 

 very much — between 1-600" and 1-140". 

 Perty affirms that E. lixjalina is a mere 

 variety of this species, and that Am- 

 hly aphis viridis (x\t:ii. 45) is the same, 

 for he has witnessed the same individual 

 Euglena produce both Euglena and Am- 

 bli/ophis. This observer has found E. 

 viridis at an elevation of 9000 feet, on 

 the Alps. On the surface of ponds at 

 Hampstead and elsewhere, common. 



E. Spirogyra (x\t:ii. 52). — Extensible 

 and cylindrical ; very finely striated and 

 granulated. The head is a little trim- 

 cated, and the hinder part attenuated 

 into a short pointed tail; colom' a 

 brownish green ; motion like E. deses. 

 Its colour varies from a beautiful green 

 to yellow or brown. It always occurs 

 singly. E. oxyuris (Smarda) is not 

 specifically distinct. Amongst Confervas 

 and Bacillaria. 1-240" to 1-120". 



E. Pyrmn (xvin. 41, 42). — Obliquely 

 fluted: when distended, oval or pear- 

 shaped. The tail generally about the 

 length of the body, and pointed ; colour 

 green. Found with many other species at 

 Hampstead, but not so frequently as the 

 other species. 1-1152" to 1-864". 



E. 2)leuronectes ( Cercaria p)letironectes, 

 M.). — Compressed, ovate-orbicular, or 

 in the form of an obovate leaf; striated 

 longitudinally; colour green; tail pointed, 

 one-third or one-fourth part the length 

 of the body, and colourless. In stagnant 

 water. 1-1152" to 1-480". 



E. longicauda (xviii.44). — Mostly stiff, 

 compressed, elliptical, and leaf-like ; co- 

 lour green ; tail the length of the body. 



