DIPPING TUBES 



351 



In dealing with minute aquatic objects, and in a great variety 

 of other manipulations, a small glass si/riiHji>. of the pattern repre- 

 sented in fig. 305, and of about double the dimensions, will be 

 found extremely convenient. When 

 this is firmly held between the fore 

 and middle fingers, and the thumb 

 is inserted into the ring at the 

 summit of the piston-rod, such 

 complete command is gained over 

 the piston that its motion may be 

 regulated with the greatest nicety ; 

 and thus minute quantities of fluid 

 may be removed or added in the 

 various operations which have to be 

 performed in the preparation and 

 mounting of objects ; or any minute 

 object may be selected (by the aid of 

 the simple microscope, if necessary) 

 from amongst a number in the same 

 drop, and transferred to a separate 

 slip. A set of such syringes, with 

 I ants drawn to different degrees of 

 fineness, and bent to different curva- 

 tures, will be found to be among the 

 most useful ' tools ' that the work- 

 ing microscopist can have at his 

 command. It will also be found 

 that if a dipping tube with a glass 

 bulb have an iiidiarubber hollow 

 ball or teat attached to the top of 

 it, it will act, for the majority of 

 purposes, as well as a .syringe. 



Forceps. A iiother instrument 

 so indispensable to the microscopist 

 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. 306, of something less than the actual 

 size. As the forceps, in marine researches, have continually to be 



FIG. 304. Dip- 

 ping tubes. 



Fit;. 305. Glass 

 syringe. 



FK.. 306. 



plunged into sea-water, it is better that they should be made of bras* 

 or of German silver than of steel. since the latter rusts far more 

 readily; and as they are not intended (like dissecting force] s) to 

 take a firm grasp of the object, but merely to hold it. they may be 

 made very light, and their spring portion slender. As it is essential. 



