OF MICROSCOPIC OBJECTS. 37 



ones, are removed. A few of various sizes should always be 

 kept on hand. 



Equally necessary are fine-pointed needles. They are 

 very readily put up for use by thrusting the eye end into 

 a common penholder, so as to be firm. The points may be 

 readily renewed, when injured, on a common whetstone ; 

 and when out of use they may be protected by being thrust 

 into a piece of cork. 



In laying out animal tissues that have been stained by 

 nitrate of silver or chloride of gold, it is advisable to employ 

 a small rod of glass drawn out to a point, as the use of a 

 metallic point causes a deposit of gold or silver at the place 

 of contact, which disfigures the preparation. 



Knives of various kinds are required in some branches 

 of microscopic work; but these will be described where 

 dissection, &c., is treated at some length, as also various 

 forms of scissors. In the most simple objects, however, 

 scissors of the usual kind are necessary. Two or three 

 sizes should always be kept at hand, sharp and in good 

 order. 



A set of glass tubes, kept in a case of some sort to 

 prevent breakage, should form part of our fittings, and 

 be always cleaned immediately after use. These are 

 generally from six to ten inches long, and from one- eighth 

 l,o a quarter of an inch in diameter. One of these should 

 be straight and equal in width at both ends ; one should be 

 drawn out gradually to a fine point ; another should be 

 pointed as the last, but slightly curved at the compressed 

 end, in order to reach points otherwise unattainable. It is 

 well to have these tubes of various widths at the points, as 

 in some waters the finer would be inevitably stopped. For 

 other purposes the fine ones are very useful, especially in 

 the transfer of preservative liquids which will come under 

 notice in another chapter. 



Forceps are required in almost all microscopic manipu- 

 lations, and consequently are scarcely ever omitted from the 

 microscopic box, even the most meagrely furnished ; but of 



