GROMIA. 



] 



GUTTA-PERCHA. 



Hedwig and Scliwaegviclien are placed here 

 by Bruch and Schimper and C. Miiller. 



BiBL. Wilson, Bryol. Brit. 152 ; Berke- 

 ley, Handh. 287. 



CtRO'MIA, Duj. — A genus of Rhizopoda, 

 of tlie order Reticiilaria. 



(Jlnir. Carapace brownish yellow, mem- 

 branous, soft, globular or oval, with a small 

 round orihce, from which very long, fili- 

 form branched expansions with vei'y deli- 

 cate extremities protrude ; the presence of 

 a nucleus and contractile vesicle is doubtful, 

 or variable. 



G. oviformis. Carapace globular, with a 

 short neck; marine; size 1-25 to 1-12"; 

 among marine plants. 



G.fuviutilis (PI. 31. fig. 15). Carapace 

 globular or ovoid, without a neck ; fre.<h- 

 water; breadth 1-280 to 1-100". Found 

 upon Ceratophylluni. 



Schlumberger describes a freshwater 

 Gromin (liydUnd), differing from the last in 

 size (l-SGO to 1-520''), and in the carapace 

 being colourless, perhaps the young state of 

 G.Jltiviatilis. Schultze desci'ibes some new 

 marine species : G. oviformis, G. Dnjar- 

 dinii, and G.paludosa; G. terricola (Leidy) 

 is cream-coloured, and occurs in earth be- 

 tween paving-stones. " 



BiBL. Dujardin, Ann. 8c. Nat. 1835, 

 iv., Infus. p. 252 ; Schlumberger, Ann. Sc. 

 JVat. 1845, iii. 255 ; Schultze, Polyihal. 55; 

 Cienkowski, Schultze's Arch. 1876, xii. 32 ; 

 Claparede and Lachm. Inf. 465 ; Leidy, 

 Sill. Am. Jn. 1875 (M. M.'Jn. xiii. 87). 



GROWING-SLIDE.— Several modifi- 

 cations of this apparatus (Infrod. p. xxiii) 

 have been recently described. 



See Smith, Ann. N. II. 1865, xvii. 334 ; 

 Barker, Qu. M. Jn. 1866, 267; R. Beck, 

 Mic. Tr. 1866, 34; Miiller, M. M. Jn. i. 

 1869, 174 ; Maddox, M. M. Jn. 1870, iii. 

 14; Broeck, M. M. Jn. 1876, xv. 221; 

 Lewis and Cunningham, ibid. 198 ; Jn. Mic. 

 Soc. 1880, 333 ; Beale, How 8fc. 76 ; Bot- 

 terill, Jn. Mic. Soc. xix. 34 ; Dalliuger, 

 M. Mic. Jn. 1874, xi. 97. 



GUANO. — As is well Inunvn, guano is 

 imported into this country in large qu;inti- 

 ties as a manm-e. It consists principally of 

 the excrement of birds, in a more or less 

 decomposed state. It affords the micro- 

 scopist a means of procuring many foreign 

 marine Diatomaceaj, the frustules and valves 

 of which are often contained in it in large 

 numbers. The ] )ialomace,-r' nuiy be obtained 

 from guano as recommended at page 250. 



GUEMBE'LIA, limp.— A genus of Or- 



thotrichaceous Mosses, including various 

 species separated from Grimmin on account 

 of the peculiar calyptra, also the Cinclidoti 

 of P. Beauvais. 



G. orbicularis, Hmpe. = (?m«mja orbicu- 

 laris, Br. Eur. 



G. riparia=Cinclidotits riparius, Wils. 



Fig. 289. 



Fiff. 290. 



Fig. 291. 



Guembelia fontinaloides. 



Fig. 289. A fertile shoot. 



Fig. 290. Capsule with ealypti-a. Magn. 10 diams. 



Fijj. 291. Teeth from the peristome. Magn. 1.50 diams. 



G. fontinaloides (tigs. 289-91)= 0';(c/. 

 fontinaloides, P. B. 



BiBL. Wilson, Bryol. Brit. p. L39. 



GUM. — A name applied to various viscid 

 (not oily) secretions of plants. Gums have 

 no microscopic structure when pure and 

 clean, but often exhibit under the micro- 

 scope traces of structures, such as d6bris of 

 cellular tissue, filamentous Fungi, i*cc., 

 which have become imbedded in them 

 while soft. What is called gum Trnga- 

 canth consists of partly decomposed cell- 

 membranes, in a condition allied to amy- 

 loid, retaining traces of their organizatiim. 

 Sections of very soft tissues or very minute 

 objects may be made hy imbuing them with 

 or immersing them in solution of gum, and 

 allowing the whole to dry up to a tough, 

 semisolid mass, capable of being sliced with 

 a razor. The slices are freed from gum by 

 soaking in water. Gum dissolved in Gly- 

 ckhink forms an excellent medium for 

 mounting vegetable tissues. 



GUTTA-PERCHA.— A substance pro- 

 duced by the evaporation of the milky juice 

 of the Isonandra gutta, of the Natural 

 Order Sa]>i>tnceie, a native of Suuialra 

 and tlie neighbouring regions. Its relatinn 

 to the microscope arises from its use in a 



