FISHING TUBES — FORCEPS. 153 



the object up with it ; and, if this is seen to be the case, by put- 

 ting the finger again on the top of the tube, its contents remain 

 in it when the tube is lifted out, and may be deposited on a 

 slip of glass or on the lower disk of the aquatic box, or, if too 

 copious for either receptacle, maybe discharged into a watch-glass. 

 In thus fishing for any but the minutest objects, it will be 

 genei'ally found convenient to employ the open-mouthed tube c ; 

 and when its contents have been discharged, if they include but 

 a single object of the desiderated kind, this may be taken up by 

 one of the finer tubes, a, b, or, if more convenient, the whole 

 superfluous fluid may be sucked up by the mouth, and the 

 object left with no more than is suitable ; or, if there be many 

 of the desired objects in the fluid first selected, these may be 

 taken up from it, one by one, by either of the finer tubes. 



72. Forceps. — Another instrument so indispensable to the Mi- 

 croscopist as to be commonly considered an appendage to the 

 Microscope, is the Forceps for taking up minute objects ; many 

 forms of this have been devised, of which one of the most con- 

 venient is represented in Fig. 52, of something less than the 



Fio. 52. 



Forceps. 



actual size. As the forceps, in marine researches, have continu- 

 ally to be plunged into sea-water, it is better that they should be 

 made of brass or of German silver, than of steel, since the latter 

 rusts far more readily ; and as they are not intended (like dis- 

 secting forceps) to take a firm grasp of the object, but merely to 

 hold it, they may be made very light, and their spring part 

 slender. As it is essential, however, to their utility, that their 

 points should meet accurately, it is well that one of the blades 

 should be furnished with a guide-pin, passing through a hole in 

 the other. 



The foregoing constitute, it is believed, all the most important 

 pieces of Apparatus, which can be considered in the light of Ac- 

 cessories to the Microscope. Those which have been contrived 

 to afford facilities for the preparation and mounting of Objects, 

 will be described in a future chapter (Chap. V). It may be 

 thought that some notice ought to be taken of the Frog Plate and 

 Fish Pan, with the former of which many Microscopes are sup- 

 plied, whilst the latter has scarcely yet gone altogether out of 

 use. But the Author having been accustomed to gain all the 

 advantages of these, by methods far more simple, whilst at least 

 equally efficacious, does not consider them as presenting any ad- 

 vantages which render it desirable to expend time or space in 

 giving a detailed account of them ; and he will explain the 

 methods alluded to, under the appropriate head. 



