1885.] 



MICROSCOPICAL JOURNAL. 



183 



Mr. Grunow's Illuminator. 



The Abbe illuminator, as con- 

 structed by Mr. J. Grunow, has al- 

 ready been referred to in these col- 

 umns, and the method of usinp: it, as ex- 

 plained bv]SIr. Grunow, given in full.* 



This month we present an illustra- 

 tion of the apparatus, from a wood- 

 cut recently received (fig. 28) . It 

 will not 

 be neces- 

 sary to 

 enter into 

 a descrip- 

 t i o n of 

 the i n - 

 strument. 



Fig. 28. — Grunow's Abbe Illuminator 



or to enlarge upon its value. The 

 Abbe condenser, in its various forms, 

 is not only the most extensively used, 

 but it is also the cheapest and most 

 generalh' useful, condenser now offer- 

 ed to microscopists. 



o 



Notices of New Fresh-Water Infu- 

 soria. — IT. 



•BY DR. ALFRED C. STOKES. 



P/iacus acuminatns^ sp. nov. (Fig. 



0- 



Body dejDressed, broadly ovate or 

 sub-orbicular, about as long as vv^ide, 

 the ventral surface slightly concave, 

 the dorsal made convex by a sub- 

 centi'al, longitudinal keel-like eleva- 

 tion ; cuticular surface longitudinally 

 striate ; posterior extremity rapidly 

 tapering and produced centrally as a 

 very short, straight, or slightly cur- 

 ved, acuminate tail-like prolonga- 

 tion ; endoplasm colored green by 

 chlorophyll corpuscles ; pigment spot 

 usually present ; flagellum somewhat 

 longer than the body. Length and 

 greatest breadth j oVtf '^y^^^'^ • Habitat. — 

 Sluggish streams, and ponds with 

 Alyr iophylh(7n . 



* Vol. V, p. 22. 



This approaches nearest Ph. tri- 

 queter (Ehr.), S. K., differing from 

 it in the concave lower surface, and 

 the short, usually straight caudal pro- 

 longation. The presence of the dis- 

 tinct ovate chlorophyll corpuscles 

 gives the endoplasm its green color, 

 but the discs are apparently confined 

 to the part immediately beneath the 

 cuticular surface, and the Phacus is 

 therefore probably to be classed 

 among the so-called symbiotic forms. 

 The amylaceous corpuscles are ap- 

 parently two only. They are small 

 and seemingly subsphcrical. A 

 single living active individual has 

 been met with having 

 the endoplasm perfectly 

 transparent and entirely 

 colorless. The cuticu- 

 lar striations are usually 

 distinctly visible only in 

 the dead and colorless 

 bodies. 



Ophryoglena ovata, sp. nov. (Fig. 

 2). 



Body ovate, soft, flexible and some- 

 what changeable in form, about one 

 and one-half times as long as broad : 

 ventral surface somewhat flattened ; 

 both extremities usually evenly round- 

 ed, the posterior one occasionally 

 slightly and obtusely pointed, the 

 frontal one commonly the broader ; 

 cuticular surface delicately striate 

 longitudinally, the cilia fine and short ; 

 oral aperture ovate, ciliated, oblique- 

 ly placed at a short distance from the 

 frontal border, followed by a some- 

 what cui"ved, apparently ciliated 

 pharynx, posteriorly enclosing a vibra- 

 tile membrane ; contractile vesicle 

 double, spherical, situated in the an- 

 terior and posterior body-halves, fre- 

 quently stellate at diastole, and having 

 long filiform diverticula ; endoplasm 

 colorless, crowded with irregular, 

 colorless and variously tinted corpus- 

 cles ; nucleus not observed. Length 

 of body yi^ inch. Habitat. — Stilly 

 water, with Ceratophyllufn and Uiri- 

 cularia. Movements rotary. 



Of the unequal corpuscles crowding 

 the body, the smaller more nearly 



