NITRATE OF POTASH. [ 543 ] 



NOCTILUOA. 



BIBL. Harvey, Mar. Alg. 116, pi. 15 B ; 

 Phyc. Br. ; Greville, Alg. Br. pi. 12 j Thuret, 

 Ann. Sc. Nat. 4 ser. iii. 22. 



NITRATE OF POTASH. See POTASH, 

 Nitrate of. 



NITRIC ACID is useful as a reagent, 

 and for separating the organic matter of the 

 Diatomacege from the siliceous valves. 



NITZSCH'IA . A genus of Aunulata. 



BIBL. Johnst. Non-parasitic Worms, 

 1855. 



NITZSCH'IA, Denny (Liotheum). A 

 genus of Anoplura. 



N. Burmeisteri is the louse of the com- 

 mon swift (Cypselus apus~). 



BIBL. Dennv, Monogr. Anopl. 230. 



NITZSCH'IA, Hass. A genus of Dia- 

 tomaceae. 



Char. 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 

 frustules 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 view of the frustules are one or two 

 longitudinal rows of slightly elongate dots 

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

 under ordinary illumin. ; surface of valves 

 covered with smaller dots, mostly opposite 

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

 ordinary illumination. 



The frustules and valves are either linear, 

 lanceolate, or of intermediate forms, some- 

 times constricted or beaked. 



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

 &, front view) ; length 1-75" ; freshwater. 



N. lanceolata (PL 17. fig. 10: , front 

 view of frustule ; 6, 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. (PL 17. fig. 11 : a, side 

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

 rine. 



N. adcularis (PI. 17. fig. 136); 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; Hassall, 

 Alga, 435 ; Rabenh. Alg. i. 149. 



.NOBERT'S LINES and PLATES. 

 These consist of parallel bands or groups of 



parallel lines, beautifully ruled upon a slide 

 with a diamond. The bands are of equal 

 breadth, and the lines in each successive 

 band are more numerous and 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. 



Band. 



1. l-13000th 



2. l-15000th 



3. 1 -18000th 



4. l-21000th 



5. l-23000th 



6. l-27000th 



7. l-31000th 



8. l-36000th 



9. l-41000th 

 10. l-45000th 



Band. 



11. l-49000th 



12. l-52000th 



13. l-55000th 



14. l-57000th 



15. l-59000th 



16. l-61000th 



17. l-63000th 



18. l-65000th 



19. l-67000th 



20. l-70000th 



More recently, a 30-band plate has been 

 produced, in which the lines are ruled to 

 over 1-100, 000th of an inch. The exhibition 

 of these lines requires sufficient magnifying 

 power, oblique illumination, and large' an- 

 gular aperture in the object-glass. See 

 TEST-OBJECTS. Also Frey, Mikr. Pigott, 

 Mn. M. Jn. ix. 63; Robin, Mic. 313 ; Brown, 

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

 273) ; Rogers, Mn. 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. fig. 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 and 

 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 individuals ; the two 

 Noctilucae then fuse, and the nuclei become 



