228 



THE AMERICAN MONTHLY 



[December, 



2d. A block of iron six inches long, 

 four inches wide, two inches thick, 

 with a smooth surface for cooling 

 slides. 



3d. A three-inch glass funnel. 



4th. A small beaker. 



5th. A filter. For a filter, put a wad 

 of clean cotton wool into the funnel, 

 then wet the cotton with alcohol, then 

 wash out all the alcohol with pure 

 water. 



The work embraces the following 

 steps : — 



ist. Clean the slide perfectly with 

 ammonia, then rinse with hot water, 

 then cleanse with ammonia again. 



2d. Add to the salicin from one- 

 tenth to one-twentieth its weight of 

 pulverized gum arable. 



3d. Make a nearly saturated solu- 

 tion of the salicin and gum in dis- 

 tilled water, or in ice-water heated 

 to the boiling point, and carefully 

 filter the solution. 



4th. Heat this solution to 100° C. in 

 the beaker. 



5th. Pour this hot solution upon a 

 still hotter slide, and drain off. 



Only a hot solution will give bright 

 colors. 



6th. Hold the slide, and watch for 

 discs of crystals. As soon as these 

 appear, place the slide on the cold 

 iron block. 



7th. A rim is put on the crystals by 

 another heating over the lamp, and 

 another cooling on the iron. 



8th. Without delay heat a drop of 

 Canada balsam on a circular cover- 

 glass, and apply the cover to the 

 crystals. 



9th. Fasten with white zinc cement 

 by using a turn-table. 



The process described, if followed 

 with care, will yield most excellent 

 results ; perfect rosettes of crystals 

 can be readily obtained, giving bril- 

 liant effects with polarized light. 



For this process, as well as for the 

 method of mounting butterfly-scales 

 already described, I am indebted to 

 Dr. Daniel H. Briggs, of Philadelphia. 



Parasites of White Ants.* 



BY DR. AMOS SEIP. 



In taking even a superficial view of 

 the animal and vegetable kingdoms, 

 we are brought at once to recognize 

 the fact, that parasitic life, in almost 

 infinite variety, is to be found distri- 

 buted in the most wonderful manner. 

 Plants, as well as man and animals, 

 have their peculiar parasites and para- 

 sitic diseases. History furnishes nu- 

 merous examples of periods of blight 

 in the vegetable kingdom, associated 

 with epizootics among the lower ani- 

 mals, and with epidemics affecting 

 the human family ; in the study of 

 which, our favorite instrument, the 

 microscope, comes in for its due 

 share in their examination and inves- 

 tigation. Kuchenmeister and Leidy 

 have shown that each parasite has an 

 independent life ; that most animals 

 have their own peculiar parasites ; that 

 even parasitic animals and plants are 

 infested with parasites ; thus proving 

 the truth of the couplet, here slightly 

 altered from its original form : — 



" Big fleas have little fleas 



" To torment and bite them, 



" And little fleas have lesser fleas, 



" And so ad infinitum ." 



I would not propose, even if time 

 permitted, to enter upon a discussion 

 or description of parasitic animals in 

 general, for the field is well nigh inex- 

 haustible ; but having found an oppor- 

 tunity to collect a few specimens of 

 the white ant a few days since, I en- 

 joyed the rare sight of examining the 

 wonderful parasites with which they 

 are infested. 



To our distinguished countryman, 

 Dr. Leidy, belongs the honor of this 

 discovery, and to his work, giving their 

 history and description, I am indebt- 

 ed for whatever I may say concern- 

 ing them. The white ant, Tertties 

 flavipes, is to be found in the dry, 

 sandy forests and fields of southern 

 New Jersey. Those here exhibited 

 were found in the vicinity of Budd's 



* Read before the New York Microscopical 

 Society, November 18th, 1881. 



