AGLAOPIIENIA. 



AIR. 



Foraminifera in D'Orbigny's classification 

 (1825). It may be said to comprise Cor- 

 ttitsjrira, Miliola (subgenera Uniloculina, 

 Jji/oculina, Triloculina, Quinqueloculina, Spi- 

 rolocuUnO) GructtocvUna), Hauerina, and 

 Fabularw, members of the family Miliolida, 

 as established bv Carpenter. The peculiar 

 ball- of- thread-like folding of the segments, 

 whence the name, is constant in the three 

 last-named genera; but in Cornuspira it is 

 merged in a discoidal spire at an early stage 

 of growth. 



BIBL. D'Orbigny, Foram. Ciiba, p. 145 ; 

 Foram. Canaries, p. 140 ; Foram. Amerie. 

 p. 68 ; For. Foss. Vienn. p. 255 j William- 

 son, Brit. Foram. p. 78, &c. ; Carpenter, 

 Int. Foram. p. G6. 



AGA'VE. See FIBROUS STRUCTURES. 



AGLAOPHE'NIA, Larnx (Pfr.). A 

 genus of Polypi, of the family Plumula- 

 riidae. It consists of Phimularia crixfata, 

 myriophyllnm, and pennatula (Johnston). 

 See PLUMULARIA. 



BIBL. Hincks. Brit. Hydr. Zooph. p. 284, 

 pis. 63 & 64. 



AGLAOS'PORA, De Notaris. A genus 

 proposed for Spharia profusa, on account of 

 the asci containing only 4 sporidia ; but 

 Tulasne has extended it to some species 

 with eight sporidia, on account of the rela- 

 tion of the pycnidia to the perithecia. The 

 brown spores of A. prof lisa, which is not 

 uncommon on Robinia pseudacacia, are 

 beautiful microscopic objects. 



BIBL. Tulasne. Sel. Fung. Carp. ii. p. 158. 



AGO'NIUM, (Erst. A genus of Con- 

 fervoid Algae, fam. Oscillatoriaceae. 



Char. Filaments very slender, rigid, 

 flexuous, tufted, jointed ; a single sporidium 

 in each joint. 



A. centrale (PL 3. fig. 1). Marine ; 3- 

 6'" long; attached to stones. 



BIBL. Rabenhorst, Alg. ii. 160. 



AG'RION. A genus of Neuropterous 

 Insects. See LIBELLULID-E. 



AGY'RIUM, Fr. A genus of Lichena- 

 ceous Lichens, tribe Graphidei. 



1 sp., A. rufum. Thallus forming 

 whitish spots; a'pothecia bright red. On 

 old posts. 



BIBL. Leighton, Lick. Fl., p. 392. 



AINAC'TIS, Kiitzing. A genus of Os- 

 cillatoriaceous plants growing on stones in 

 alpine streams. The two known species 

 have been found in Britain. 



A. alpina. Fronds from 1-12 to 1-2" in 

 diameter, often confluent, formed of re- 

 peatedly dichotomous filaments, dark olive 



green, containing separate particles of car- 

 bonate of lime. Hassall, Brit. Fr. Alijrr, 

 Ixv. 1. 4; Kutz. Tab. Phyc. vol. ii. pL 68. 

 1 ; Zonotrichiu hatmatites, Rabenhorst, Ala. 

 ii. 212. 



A. cakarea, Kiitz. Fronds 1-4 to 1-2" 

 in diameter, orbicular, convex, ultimately 

 confluent, sometimes greenish, often dark 

 chestnut, composed of dichotomous fila- 

 ments, at length incrusted continuously \\ith 

 carbonate of lime. Kiitzing, /. c. pi. 63. 2 ; 

 Z. calc. Rab. ; Lithonema calcaria, Hassall, 

 tab. Ixv. fig. 2. 



Kiitzing states that the gelatinous sheaths 

 of the filaments of A. alpina have a spiral- 

 fibrous structure. See SPIRAL STRUC- 

 TURES. 



AIR. It need scarcely be remarked that 

 the air consists essentially of a mixture of 

 two gases, oxygen and nitrogen, in the pro- 

 portion by volume of about 21 parts of the 

 former to 79 of the latter, with variable 

 quantities of gaseous carbonic acid (about 

 l-2000th) and aqueous vapour. As the 

 component molecules of gases are invisible 

 with any powers of the microscope, the air 

 possesses no microscopic characters. In two 

 respects, however, the study of the air is of 

 great importance : 1st, in regard to the op- 

 tical appearances produced by the passage of 

 light through it when contained in bodies 

 submitted to microscopic examination ; and 

 2ndly, in regard to the particles which are 

 always, in greater or less numbers, sus- 

 pended in it. 



In microscopic investigations, we meet 

 with air either existing in cells or cavities 

 in various tissues, or in the form of bubbles, 

 confined by the liquid in which the objects 

 are usually immersed. When surrounded 

 and confined by liquid, it mostly assumes a 

 spherical form, in accordance with the law 

 of hydrostatics, that the pressure of fluids 

 is equal in all directions ; sometimes the 

 spherical form is exchanged for that of a 

 compressed or oblong spheroid, the result of 

 the pressure of the glass slip covering the 

 object. When confined, in cells or cavities, 

 it assumes the form of these. It is in ge- 

 neral easily recognized by transmitted light 

 from the smooth and even darkness or 

 shading given to its margins, whilst in the 

 centre it appears luminous and clear. Some- 

 times the dark margins of air-bubbles have 

 a pale purplish-yellow, blue or greenish 

 tinge. By reflected light, of course, no dark- 

 ness is produced, but it then appears vitre- 

 ous and shining, in consequence of the re- 



