MICROSCOPICAL COLLECTIONS IN FLORIDA. 135 



threads of the mould fungus will be sure to creep over the surface 

 of the leaves, spoiling them for microscopical material, if they 

 are not quickly and effectually dried. For this purpose it is well 

 to have a good supply of the bibulous botanical paper, and to 

 change the specimens every day to fresh sheets for at least four 

 or five days. The sheets after being once used, should be spread 

 out in the sun to dry. A weight of about thirty pounds may be 

 used for the pressure. 



The objects heretofore mentioned are all for opaque mounting. 

 Almost every preparer of slides has his own favorite method for 

 this kind of work. I myself prefer the use of the transparent 

 shellac cells. Clarified shellac is dissolved in alcohol, and filtered 

 through cotton-wool under a bell glass, and with the application 

 of heat. The solution is evaporated down until it is so thick 

 that it will only just run almost a jelly. In this condition it 

 can be put on a slide with a camel's hair brush, on the turn-table, 

 and very quickly worked up into a ring with the point of 

 a knife, used first on the inside to make the cell of the size 

 wanted, and then on the outside to turn the cement up into 

 a compact ring. Two or three applications of the cement, with 

 intervals of a day or two after each, will make cells of sufficient 

 depth for all ordinary specimens. These cells dry quite slowly ; 

 and if artificial heat is used, it must be increased only very 

 gradually, otherwise vapor of alcohol bubbles will make their 

 appearance in them. A small ring of Brunswick black may be 

 made inside of the cell, to which w r hen thoroughly dry, the 

 object may be fastened with a very little liquid marine glue. In 

 this case both sides of the leaf can be seen, which is often 

 desirable. In all opaque mountings a minute aperture should in 

 some way be left open into the inside of the cell, so that it shall 

 not be hermetically sealed up. This little precaution will save 

 an innumerable number of failures. 



The collector in Florida, will not fail to secure- a supply of the 

 leaf stems of the castor oil plant (Ricimis communis). In 

 regions be}^ond the influence of frosts, this plant grows contin- 

 uously from year to year and becomes quite a tree. It is only in 

 such a growth that the spiral tissue of the fibro-vascular bundles 



