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 
to 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 
