INVERTEBRATA, CRYPTOGAMIA, MICROSCOPY, ETC. 503 



fimncl is uppermost, and some spuu glass is pressed into the lower 

 conical part of the filter. 



In using the apparatus the funnel is filled with glycerine-gelatine, 

 and the bottle with hot water, which runs otf slowly through the tube 

 in the first hole and is constantly replenished. The glycerine-gelatine 

 is thus kej)t fiuid, and drops in a clear condition into a vessel placed 

 below to receive it. Some drops of carbolic acid should be added to 

 the fluid product of the filtering. 



The method of using it given by Herr Bachmann* is as follows : — 



" A piece of the glycei'ine-gelatine of sufficient size is taken with 

 a scalpel and placed in the middle of the slide, and the whole of the 

 middle part of the slide is Avarmed uniformly. It is thereby melted, 

 and spreads. The object is then put in the fluid, and a small piece of 

 glycerine-gelatine added ; it is again warmed slightly, so that the 

 fluid may thoroughly penetrate the object. The slide is then laid on 

 something black, whereby the air-bubbles present become plainly 

 visible. By the blade of a scalpel these are drawn out of the fluid, 

 and at the opposite side the cover-glass, slightly warmed, is placed 

 in a slanting jjosition, and gradually brought liorizontal. By tliis 

 means any remaining air-bubbles arc all driven in one direction, and 

 by a slight pressure on the loose cover-glass may be pushed from 

 under it. An essential point for the success of the whole manipula- 

 tion consists in using more glycerine-gelatine on the slide than is 

 required for tlic mounting, the circle formed by it being larger than 

 the cover-glass, so that the air-bubbles may be pushed from under the 

 cover into the liquid outside it. If any air-bubbles remain not- 

 withstanding under the cover, the slide should be warmed again, the 

 cover-glass raised again with a fine needle, so that a little of the 

 mounting material can get under, and the cover-glass repeatedly 

 pressed at the side opposite to the air-bubbles until tliey are pushed 

 from iinder the glass. The slower and more uniformly the slide is 

 warmed, the fewer air-bubbles will be formed. 



It may happen that from the object not being properly penetrated 

 by the embedding substance, small air-bubbles, or water or glycerine 

 globules may be formed in the preparation after it has set. Before 

 the slide is varnished, these should be carefully looked for under 

 the Microscope." 



Herr Brandt further says that it is very difficult, by merely placing 

 the object in the glycerine-gelatine on the slide, to be sux-o that it will 

 be thoroughly jjcnetrated. It should therefore be placed first in a 

 small wide-mouthed bottle of glycerine-gelatinc,of thesame consistency 

 as that used for the mounting, which has been melted on the hot-plate 

 described by l)onnadicu,f particular care being taken that it is heated 

 only a little beyond the melting point of the glycerine-gelatine. 

 When the object appears to bo Kuthcicntly j)cnetratcd, it is taken out 

 inid placed on the slide, and is then ready for mounting in the manner 

 above described. 



" After a few hours (continuing Ilcrr Bachmann's description), the 



♦ 'Loitfudcn z. AnfcrtiKiuif? Mikr. Dauorpiiiparati',' Svo, IMimicli, 1S7D. 

 t ' ZeitBolir. f. Mikr.,' i. p. hO. 



