19 



M<H \TI.\<; vv.s.sr /;>-. 



B 



This box will be found most use- 

 ful for various purposes in the labor- 

 atory. The object in the box can be 

 !D arranged by the use of hot needles, 

 while the paraffine is yet in a liquid 

 state. As soon as a film is formed 

 over the paraffine, it is plunged into 

 cold water to harden quickly and 

 thus prevent the mass from becom- 

 ing filled with air spaces. After the 

 paraffine has become hard it can be 

 readily removed from the box and 

 fastened in a microtome for section- 



A B ing- 



Fig. 2. Diagram to show the lines of 

 folding in making a paper boat. 



Several different forms of microtomes are highly recommended. 

 Minot's is certainly one of the best. A very inexpensive well micro- 

 tome will answer the purpose. In case the latter is used the block 

 containing the object should be cut down until it will fit in the well 

 where it is fastened by pouring over it pure melted paraffine. It is 

 best that a microtome with movable jaws be used in order that the 

 position of the object can be changed to vary the angle of section- 

 ing. This is especially important in lougisections of roots or 

 stems. If longisections of a root are being made or the whole of 

 an object is to be studied, it is advisable that a series be made and 

 only those need be mounted which contain the structure desired. 

 In order to stain and clear the sections it is necessary that they be 

 in some way glued to the slide. This can be accomplished in sev- 

 eral ways. Those methods to be especially recommended are as 

 follows: With a camel's hair brush spread over the slide a very 

 thin layer of a mixture of equal parts of clove oil and 2 per cent. ' 

 collodion. Place the sections on the slide and press them gently 

 against it with a brush or any soft object. The preparation is then 

 put in an oven with the temperature at 50 C. for 20 minutes, or 

 until the paraffine has melted and the clove oil evaporated. The 

 sections will then have become fastened to the slide and can be 

 stained and washed without danger of loosening. The same result 

 can be more quickly obtained by heating the slide very cautiously 



