TriE Microscope. 291 



mounting can sometimes be obtained ; or soaking tlie roots of 

 parsnip, okra, turnip, radisli, &c., in a dilute solution of bicliro- 

 mate of potash (Miiller's solution) 'for a day or so prior to 

 making sections, will toughen the tissues and give better results. 

 I found that while dilute alcohol hardened the worms, so they 

 were easy to' manage, it caused a perceptible shrinkage and dis- 

 tortion, which Miiller's fluid did not. 



In practice, it will be advantageous to keep a quantity of 

 roots of okra, cow pea and the like in water. They will soon 

 decay enough to permit separation of the tissues, and the task 

 ©f finding specimens will be much easier than in fresh roots. 



To mount these fragile and elusive worms requires infinite 

 tact, and if the student succeeds one time in fifty he is to be 

 congratulated. I found this method, on the whole, the most 

 successful : Build up a shallow cell with gold size, till it is six 

 to eight millimetres in depth, let it dry till slightly " tacky." 

 With a fine needle detach a small portion of the decaying tissue 

 around the gravid, visible worms ; add barely a drop of water 

 on the slide, and tease apart the fragment with needles, so as to 

 cover thinly the cell ; add either the gum and glycerine or 

 gelatin glycerine to nearly fill the cell, avoid bubbles, apply the 

 cover-glass and press it into the " tacky " border ; wipe off the 

 superfluous medium, let it dry for an hour or so, and finish with 

 a varnish or Brunswick black. Sounds easy, does it not, yet 

 how many the slips ! 



In a gold size cell, a drop of the " sediment " previously 

 referred to, with an equal quantity of glycerine, occasionally 

 gives a good mount, and for short periods a little of the sedi- 

 ment with a drop of " carbolated water," two per cent, solution, 

 does very well. Tor temporary use, a drop of the sediment, 

 diluted with clear water on a slide without a cover, may show a 

 fine specimen, using a- low power, say one inch objective; then 

 by careful manipulation it may be isolated from extraneous 

 matter, the moisture absorbed by blotting paper, a small quan- 

 tity of medium as glycerine jelly cautiously placed around the 

 object, a drop placed on a clean cover-glass, which is turned over 

 on the slide, and all gently warmed till it flows together. A few 

 bubbles, more or less, ought not to count, for it is nearly impos- 

 sible to avoid them. Use a fine camel-hair brush with warmed 

 jelly to surround the object, let it cool before further action. 



