ILLUMINATION. 



INFLAMMATION. 



Lichens, described as consisting of irregular 

 spores, at first involved in a globule of 

 mucus, and afterwards glued together in 

 simple mealy patches (these plants seem 

 very obscure). Four species are described 

 as British : 



I. roseum, Fr. (Grev. So. Crypt. FL pi. 51) . 



/. carneum, Fr. (Oorda, Ic. Fung. iii. 

 fig. 1). 



I. corallinum, Rob. (Desmaz. Exsicc. no. 

 1551). 



I. coccineum, Fr. (Cord. /. c. fig. 3). 



BIBL. Op. cit. and Berk. Br. Flora, ii. 

 pt. 2, 328 ; Ann. N. H. 1850, v. 466 ; Fries, 

 Sum. Veg. 482 ; Syst. Myc. iii. 259. 



ILLUMINATION. This has been 

 specially alluded to in the Introduction 

 (p. xxviii), and in the articles ANGULAR 

 APERTURE, DIATOMACEJE, POLARIZATION, 

 and TEST-OBJECTS. But several papers 

 have been published in recent years, de- 

 scribing new and ingenious methods of 

 illuminating the finer and more difficult ob- 

 jects, to which we can only refer. 



BIBL. Higgins, Qu. Mic. Jn. x. 150; 

 Abbe, M . M. Jn. xiii. 77 ; Smith, ib. 88 ; 

 Wenham, ib. 156, & Engl. Mechanic, 1877, 

 279 ; Whittell, ib. xiv. 109 ; Bramhall, ib. 

 xvi. 102 ; Osborne, ib. xvii. 179 ; Moore- 

 house, ib. xviii. 29 ; Woodward, ib. xviii. 

 61 ; Edmunds, ib. xviii. 78 ; Schulze, Jn. 

 Mic. Soc. 1878, 45. 



ILYOBA'TES, G. 0. Sars (=KRITHE, 

 B., C., & R.) -^ g erms f Ostracoda (Ento- 

 mostraca), of the family Cytheridae. Lower 

 antennae 4-, upper 5-jointed, with the 

 last three joints short and stout ; first two 

 pairs of feet three-jointed; eyes wanting. 



3 species. Recent in Norway, Britain, 

 Bay of Biscay. Fossil, Tertiary and Post- 

 tertiary, England. 



BIBL. Brady, Crossky & Robertson, 

 Post-Tertiary Entom. 1874, 184. 



ILYOCRYP'TUS, G. O. Sars. A genus 

 of Macrotrichidae (Entomostraca). 



1 species. 



Britain, Russia, Germany, Sweden. 



BIBL. Norman and Brady, Mon. Brit. 

 Entom.j Nat. H. Tr. North, vol. i. 17. 



IMPERFORATA. A division of the 

 Foraminifera, characterized by the absence 

 of pseudopodial pores or tubules in the 

 shell, which is either membranous (family 

 Gromidse), porcellaneous (fam. Miliolidse), 

 or arenaceous (fam. Lituolidae). (See 



FORAMINIFERA.) 



BIBL, Carpenter, Introd. For. 62. 



INAC'TIS, Kiitz. A genus of Oscilla- 

 toriacese (Confervoid Algae). 



Char. Filaments sheathed, indistinctly 

 jointed, parallel, sometimes dichotomous, 

 densely aggregated, and forming a pulvi- 

 nate hemispherical frond, springing from a 

 substratum of Protococcus-likQ cells. 



In pools, on other Algse ; on rocks, &c. 



3 species, with several varieties. 



BIBL. Kiitzing, Phyc. 77; Rabenhorst, 

 FL Alg. ii. 159. 



INDIA-RUBBER, or CAOUTCHOUC. 

 This substance occurs naturally in globules 

 suspended in the milky juices of many 

 plants, especially of the Orders Euphorbia- 

 ceae, Urticaceae, and Apocynaceae ; the 

 form, of the globules is varied. In PI. 48. 

 fig. 23 is represented part of a milk- vessel of 

 Euphorbia antiquorum with fine caoutchouc 

 globules. When such milky juices are eva- 

 porated, the globules become blended into a 

 uniform elastic mass, the India-rubber. 



Solution of caoutchouc is sometimes used 

 as a cement for closing glass cells ; but its 

 chief importance in this respect depends on 

 its forming a constituent of marine glue (see 

 CEMENTS). 



INDICATOR, QUEKETT'S. Is a 

 small steel moveable hand placed just above 

 the diaphragm of the eye-piece, so as to point 

 to nearly the centre of the field. 



INDIGO. This well-known vegetable 

 substance is chiefly obtained from plants of 

 the genera Indigofera and Isatis, and Poly- 

 gonum tinctorium, but may be found in many 

 others. 



It has also been found in human urine, 

 of which it is probably a normal consti- 

 tuent. Its best marked character is that of 

 subliming in flattened prisms and plates 

 (PI. 10. tig. 14). 



Indigo is sometimes used as a colouring- 

 matter for injections, and is also very use- 

 ful for colouring the internal cavities of 

 Infusoria which swallow the granules; 

 also for rendering visible ciliary motion 

 (see INTRODUCTION, p. xxxvi), &c. - The 

 simplest mode of employing it is to rub it 

 from a water-colour cake of indigo very 

 gently with a little water. The Infusoria 

 require to be left in the coloured mixture 

 some time ; and it is well to remove them 

 into clean water for examination. 



Indigo-carmine forms the basis of some 

 excellent staining solutions. 



BIBL. See CHEMISTRY. 



INFLAMMATION. The phenomena of 



