NITRATE OF POTASH. [ 6^3 ] 



NOCTILUCA. 



RiBL. Ilarvev, 3Iar. Alg. IIG, pi. 15 B ; 

 Phiic Br. ; Greville, Ahj. Br. pi. 12 ; Thuret, 

 Aivi. Sc. Nat. 4 »6v. iii. 22. 



NITRATE OF POTASH. See Potash, 

 Nitrate of. 



NITRIC ACID is useful as a reag-ent, 

 aud for separating the organic matter of the 

 Diatoiuace;« from the siliceous valves. 



NITZSCiriA.— A genus of Annulata. 



BiBL. Jolinst. Non-parasitic Worms, 

 1855. 



NITZSCIITA, Denny (Liotheum).—A 

 genus of Anoplura. 



N Bur)neisteri is the louse of the com- 

 mon swift (^Cypselus apus). 



BiBL. Denny, Monogr. Anopl. 230. 



NITZSCII'IA, Hass.— A genus of Dia- 

 tomaoefe. 



C7iar. Frustules free, single, compressed, 

 usually elongate, straight, arched, or sig- 

 moid, with a longitudinal, not median, ex- 

 ternal keel (? ), and one or more longitudi- 

 nal rows of puncta ; suture in front view of 

 frustides not median. 



The valves have no nodules; we have 

 not been able to satisfy ourselves of the 

 presence of the external keel ; upon the 

 portions of the valves forming the middle of 

 the side \dew of the frustules are one or two 

 longitudinal rows of slightly elongate dots 

 or puncta (PL 17. fig. 10 d), often visible 

 under ordinary illumin. ; surface of valves 

 covered with smaller dots, mostly opyjosite 

 (not quincuncial) (fig. 10 d), invisible under 

 ordinary illmniuation. 



The frustules aud valves are either linear, 

 lanceolate, or of intermediate forms, some- 

 times constricted or beaked. 



N. sigmoidea (PI. 17. fig. 9 : a, side view; 

 b, front A"iew) ; length 1-75" ; freshwater. 



N. hniceolata (PI. 17. tig. 10: a, front 

 view of frustule ; b, front view of single 

 valve ; c, side view of frustule) ; length 

 1-150" ; fig. 10 d exhibits the two kinds of 

 markings as seen with the stops. Marine. 



N. birostrata, Sm. (PI. 17. fig. 11 : a, side 

 view; b, front view); length 1-70"; ma- 

 rine. 



N. acicidaris (PI. 17. fig. 13 6); length 

 1-.300"; freshwater. 



N. reversa (PL 17. fig. 12) ; brackish 

 water. 



N. tcenia (PL 17. fig. 13 a); length 

 1-250" ; brackish water. 



BiBL. Smith, Br. Diat. 37 ; HassaU, 

 Ah/a, 4.35; Rabenh. Alg. i. 149. 



NOBERT'S LINES and Plates.— 

 These consist of parallel bauds or groups of 



parallel lines, beautifully rided upon a slide 

 with a diamond. The bands are of equal 

 breadth, and the lines in each successive 

 baud are more numerous aud closer than in 

 those of the preceding. In the 20-band 

 plate, R. Beck determined the distances of 

 the lines to be as follows, in fractions of an 

 inch. 



More recently, a 30-band plate has been 

 produced, in which the lines are ruled to 

 over l-100,000th of an inch. The exhibition 

 of these lines requires sufiicient magnifying 

 power, oblique illumination, and large an- 

 gular aperture in the object-glass. See 

 Test-Objects. Also Frev, MiJcr. ; Pigott, 

 Mri. M. Jn. ix. 63; Robin, "Mic. 313 ; Brown, 

 Pr. Roy. Soc. xxiii. 531 {Mn. M. Jn. xv. 

 27.3) ; Rogers, 3In. M. Jn. xvi. 74 ; Webb, 

 ibid. xvi. 171 ; Beck, Micr. 1865, 19. 



NOCTILU'CA, Suriray.— A genus of 

 marine Protozoa, now usually referred to 

 the Infusoria. 



N. miliaris (PL 53. %. 23) is rounded, of 

 about the size of a pin's head, with a ten- 

 tacle-like, transversely striated, curved pro- 

 process, by means of which it propels itself 

 through the water. Near its attachment is 

 the mouth, on one side of which is a tooth- 

 like projection. The mouth leads by means 

 of a tubular gullet to an irregular hollow 

 stomach in the sarcode of the interior of the 

 animal ; and there is a definite anal opening. 

 The body consists of a radiating protoplas- 

 mic network. There is a nucleus; but no 

 vacuoles have been observed. The part to 

 which the tentacle is attached is plicate aud 

 depressed, so as to render the body some- 

 what bilobed ; it has no carapace. 



Multiplication takes place by subdivision 

 and internal gemmation. Sexual union 

 also takes place, the animals placing their 

 oral apertures close to one another, a proto- 

 plasmic bridge being formed, which unites 

 the nuclei of the two indi\iduals ; the two 

 Noctilucse then fuse, aud the nuclei become 



