GROMIA. 



[ 366 ] 



GUTTA-PERCHA. 



Hedwig and Schwaegrichen are placed here 

 bv Bruch and Schimper and C. Miiller. 



" BIBL. Wilson, Bryol Brit. 152 j Berke- 

 ley, Handb. 237. 



GRO'MIA, Duj. A genus of Rhizopoda, 

 of the order Reticularia. 



Char. Carapace brownish yellow, mem- 

 branous, soft, globular or oval, with a small 

 round orifice, from which very long, fili- 

 form branched expansions with very 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.flumatilis (PI. 31. fig. 15). Carapace 

 globular or ovoid, without a neck ; fresh- 

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

 upon Ceratophyllum. 



Schlumberger describes a freshwater 

 Gromia (hyalina), differing from the last in 

 size (1-860 to 1-520''), and in the carapace 

 being colourless, perhaps the young state of 

 G.flumatilis. Schultze describes some new 

 marine species : G. oviformis, G. Dujar- 

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

 is cream-coloured, and occurs in earth be- 

 tween paving-stones. 



BIBL. Dujardin, Ann, Sc. Nat. 1835, 

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

 Nat. 1845, iii. 255 ; Schultze, Polytkal. 55; 

 Cienkowski, Schnitzels Arch. 1876, xii. 32 ; 

 Claparede and Lachm. Inf. 465 ; Leidy, 

 Sitt. Am. Jn. 1875 (M. M. Jn. xiii. 87). 



GROWING-SLIDE. Several modifi- 

 cations of this apparatus (Introd. p. xxiii) 

 have been recently described. 



See Smith, Ann. N. H. 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 $c. 76 ; Bot- 

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

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



GUANO. As is well known, guano is 

 imported into this country in large quanti- 

 ties as a manure. 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 Diatomaceae, the frustules and valves 

 of which are often contained in it in large 

 numbers. The Diatomaceae may be obtained 

 from guano as recommended ait page 250. 



GUEMBE'LIA, Hmp. A genus of Or- 



thotrichaceous Mosses, including various 

 species separated from Grimmia on account 

 of the peculiar calyptra, also the CincUdoti 

 of P. Beauvais. 



G. orbicularis, Hmpe.= 6rnmmtVz orbicu- 

 laris, Br. Eur. 



G. riparia = Cinclidotus riparim, Wils. 



Fig. 289. Fig. 290. Fig. 291. 



Guembelia fontinaloides. 



Fig. 289. A fertile shoot. 



Fig. 290. Capsule with calyptra. Magn. 10 diams. 



Fig. 291. Teeth from the peristome. Magn. 150 diams. 



G. fontinaloides (figs. 289-91)= Cincl 

 fontinaloides j P. B. 



BIBL. Wilson, Bryol. Brit. p. 139. 



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 debris of 

 cellular tissue, filamentous Fungi, &c., 

 which have become imbedded in them 

 while soft. What is called gum Traga- 

 canth consists of partly decomposed cell- 

 membranes, in a condition allied to amy- 

 loid, retaining traces of their organization. 

 Sections of very soft tissues or very minute 

 objects may be made by 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- 

 CERINE 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 Sapotacese, a native of Sumatra 

 and the neighbouring regions. Its relation 

 to the microscope arises from its use in a 



