INULINE. 



[ 441 ] 



ISARIA. 



The capillaries of tlie intestines are very 

 beautiful when injected ; hut great care is 

 required in securing the vascular branches, 

 to prevent the escape of the injection. 



Two thick layers of ganglionic nervous 

 masses are distinguislmble in the intestines. 

 One is situated in the submucous tissue, the 

 other between the circular and longitutliual 

 muscular fibres. The former is a fiat layer 

 with a few ganglia projecting towards the 

 mucous membrane and penetrating among 

 the follicles; the latter is more irregular, 

 and presents nodulated ganglionic masses. 

 The ganglia give ofi" and are traversed by 

 nerves that form a plexus, some joining the 

 ganglionic layers, others uniting with the 

 mesenteric nerves. The nerves are non- 

 medullated. 



BiBL. Kiilliker, Mikr. Anat. ; Verson, 

 Strieker's Hist. ; Frey, Hist., (^- the full 

 literature. 



IN'ULIXE.— A substance allied to 

 starch, occurring in solution in the cell- 

 contents of plants, especially the Compo- 

 sitae, as the Dahlia, dandelion, &c. ; it is 

 coloured yellow by iodine. It forms crys- 

 talloids or sphaerocrystals resembling those 

 in PI. 39. fig. 11; "^and they exhibit the 

 black cross with polarized light. In a 

 section of a tuber of the Jerusalem arti- 

 choke, macerated in spirit, they will be 

 foimd in the cells, and may be mounted in 

 glycerine. 



BiBL. Gmelin, Cliemie, vii.; Prautl, /;»///«, 

 1870; Dragendorfi; Material. 8fc., 1870; 

 Sachs, Bot. 1874. 



IODINE. — Solution of iodine is often 

 useful for dyeing and rendering very trans- 

 parent objects more distinct, and for its 

 producing with some vegetable and animal 

 tissues and substances colours by which 

 they may be distinguished. The general 

 results of its action are enumerated in the 

 Introdlx'tion ; and special remarks are 

 made under the heads of the tissues. 



An aqueous solution of iodine is the best 

 for general use ; but a solution in spirit is 

 much stronger. A very strong solution may 

 be made by dissolving iodine in a solution 

 of iodide of potassium ; this may be used 

 for dveing tissues, but not for the detection 

 of cellulose, as the precipitated iodine gives 

 a bluish tinge to the structure. Solutions 

 of iodine in chloride of zinc, and of iodide 

 of zinc are valuable reagents for cellulose. 

 See Schultze's Test. 



Iodized serum is made of amniotic fluid 

 (calf) and a small quantity of strong tincture 



of iodine. It has a pale yellow tint. It is 

 used as but little altering the appearances 

 of delicate objects. 



An artificial substitute may be made 

 with 1 oz. of white of n^^, 30 grs. of salt, 

 8 oz. of water, enough tincture of iodine to 

 colour, and 2 or 3 drops of carbolic acid, the 

 whole to be well shaken and filtered. 



IRID^E'A, Bory. — A genus of Cryptone- 

 miacepe (Florideous Algae), containing one 

 common British species, I. edulis, a dull-red, 

 obovate, leaf-shaped sea-weed of fleshy-car- 

 tilaginous texture, 4-18" long, the central 

 substance composed of longitudinal, the 

 cortical of closely-packed moniliform per- 

 pendicular filaments. Fructification : sj307-es 

 in spherical masses [favellidia), imbedded in 

 the frond in wide patches near the extre- 

 mity ; tetraspores in dense band-like im- 

 mersed sori. 



BiBL. Harvey, Mar. AUj. 160, pi. 19 A ; 

 Phjc. Brit. pi. 97; Greville, Alg. Brit. 

 pi. 17; Eng. Bot. pi. 1.307. 



IPtlDES'CENCE. See Intkoduction, 



p. XXXV. 



IRIS. See Eye, p. 311. 



ISARIA, Hill. — A genus of Isaeiacei 

 (reputed Hyphomycetous Fungi), growing 

 upon dead insects, fungi, or twigs or leaves 

 of plants. I. farinosn, Fries, grows to a 

 height of 1-2" on dead pupte, spiders' nests, 

 &c. /. arachiwphila, Ditton, intricata, Fr., 

 puherula, Berk., and Friesii, Montague, are 

 also British, /. citrina (figs. 374, 375) is a 



Fig. 374. 



Isaria citrina. Plants on a fungus. Natural size. 



small species, growing gregariously on ve- 

 getable substances. 



Tulasne has recently published an inter- 

 esting paper on Isaria, showing that at any 

 rate some of the forms referred to this genus 

 are conidiiferous fruits of certain Sphcerice — 

 in particular that Is. crassa (farinosa, Fr.) 

 is a form of Spha-ria inHitaris. This plant is 

 found most frequently on the larvas of Bo77i- 

 hyx Buhi; and the first sign of its growth is 

 the formation of a mildew, between the 

 rings of the abdomen, very much resembling 

 a Botrytis. Subsequently the body of the 

 larva, quite filled up and rigid with mycelial 



