ii6 



THE AMERICAN MONTHLY 



[June. 



in this region, in birds and reptiles, 

 contrary to the cilia of the auditor}' 

 cells, which seem to have lost their 

 automatic movement and to be de- 

 pendent upon special forms of irrita- 

 tion. 



Rochester, N. Y. 



Eveniugs with the Microscope. 



I 



It is proposed to publish under the 

 above heading, a number of articles 

 especially intended for the beginner 

 in the use of the microscope. Those 

 who have attained more or less profi- 

 ciency in microscopical work, know 

 that there is never a dearth of mate- 

 rial for entertainment as well as in- 

 struction always available. Yet many 

 who, having their interest aroused by 

 a glimpse of some of the wonders it 

 reveals, forthwith purchase an instru- 

 ment, soon lay it aside, because they 

 find nothing new to examine. They 

 find nothing new because they have 

 not been guided in their search for 

 it. Perhaps we may be able to show 

 them that they need never search in 

 vain. If in the dead of winter there 

 is a dearth of insect and plant life 

 without, there may still be found 

 enough indoors to engage many profi- 

 table hours over the tube. This is 

 especially true in the country, where 

 in barns and sheds may be found, 

 concealed among the rafters or shel- 

 tered under the eaves, cocoons, and 

 nests of insects, and spider's webs, 

 which, if examined with the aid of 

 some good book as a guide, will well 

 repay a careful search. On boards 

 and trees will be found lichens and 

 dried-up mosses, and here and there 

 the brown or white excrescences, 

 often several inches in breadth and 

 thickness, which are fungus-growths, 

 and green spores of algae, with many 

 other things well worthy of examina- 

 tion. 



The first object we will describe is 

 the eye of a common house-fly. The 

 two large, hard, rounded prominences 

 on the head of a fly are the com- 



pound eyes. The usual way of pre- 

 paring them for microscopic speci- 

 mens is to first cut them out as 

 carefully as possible, so as not to in- 

 jure them, and place them in a strong 

 solution of caustic potash, where they 

 should remain until they become 

 slightly softened, which will be in 

 about twelve hours. The softening 

 can be hastened by gently heating 

 the solution. Then take out one of 

 the eyes, wash it in water to remove 

 the potash, then place it in a watch- 

 glass on a piece of white paper, or in 

 a small porcelain dish, and wash it 

 thoroughly by the aid of a common 

 camel-hair brush, until all the shreds 

 of tissue are removed, and the chi- 

 tinous portion of the eye is perfectly 

 clean. This can only be known by 

 examination with the microscope. 



When perfectly clean, the eye is 

 ready to be permanently mounted. 

 For this purpose it must be spread 

 out flat on the slide, and to do this 

 without splitting the specimen re- 

 quires great care. Trim off the 

 edges smooth, and lay the speci- 

 men, rounded side up, upon a slip 

 of glass about an inch square : 

 cover it with another square of glass 

 of the same size, and gently press the 

 two together. If the specimen has 

 been sufficiently softened by the 

 potash, it will spread out quite flat. 

 The two pieces should be then bound 

 together by thread, and plunged into 

 a bottle of alcohol. The alcohol re- 

 moves the water and hardens the 

 specimen, so that it retains its flat- 

 tened form. It should remain in the 

 alcohol, at least, twelve hours. It is 

 then removed from between the 

 glasses and transferred to strong 

 carbolic acid for a few moments. A 

 drop of Canada balsam is placed in 

 the centre of a slide and the speci- 

 men is placed upon it, previously 

 removing the adhering carbolic acid 

 by touching it with blotting paper. 

 By applying gentle heat, the balsam 

 becomes very fluid and entirely en- 

 velops the eye; a thin cover-glass is 

 then applied, the eye is arranged in 



