122 THE AMERICAN MONTHLY [July, 



I. Microscope with high (^) or low powers (i) . 3. A number of clean 

 slides and covers. 3. ^ dozen watch-glasses. 4. A supply of bibulous paper. 

 5. Two dropping tubes and a couple of glass stirring rods. 6. A glass ot 

 water. 7. Some vinegar. 8. Reagents as follows : — i. Glycerine or glyce- 

 rine jelly. 2. Alcohol. 3. Acetic acid. 4. Eosine. 



The first step is the acquisition of skill in catching the material for study. 

 To acquire this proceed as follows : — With one of the dropping tubes lift a 

 drop from the sediment in the bottom of the supply. Catch this on the cen- 

 tre of one of the slides. Place the slide on the stage of the microscope and 

 examine the uncovered drop with the low power, moving the slide about back- 

 ward and forward with the sediment in sharp focus. If involved in the 

 sediment is a long and narrow thread-shaped translucent body in quick mo- 

 tion, it is almost certainly the object of search. If one or more are not seen 

 after the first lot has been searched through, try it over again until one of the 

 wriggling bodies has been found. Having found one with the low power, 

 hold the slide over a dark background. A piece of black cloth, or a black 

 tile, is good for the purpose. Try to see the worm with the naked eye. One 

 will soon succeed in doing this after having learned the sinuous motion which 

 is habitual to the worm. Having acquired the necessary practice in detect- 

 ing the specimen with the naked eye, collect an abundant supply for future 

 use. 



To do tins, examine closely the vessel of vinegar. On the surfoce and on 

 the side toward the window or source of light probably a great many of the 

 eels are swimming actively about. With the pipette suck up a few of these 

 and drop them into a watch-glass of pure water. When there have been 

 removed to the pure water a dozen or so of the largest of the eels there is 

 then sufficient supply of material for study. This process could not occupy 

 the expert more than five minutes. It has a value in teaching carefulness 

 and skill in delicate manipulation as well as in securing material for study. 



Next, with the pipette, lift out of his watch-glass prison one of the eels and 

 deposit it with the least possible fraction of a drop of water on a fresh dry slide. 

 If the slide be moist the water will spread out over it in every direction, but 

 if dry then it will remain in a small spot. Pour out a little alcohol into a 

 watch-glass and add to it several drops of strong acetic acid. This is a kill- 

 ing fiuid. Alcohol alone would be deadly, but of slower action. Place, a 

 drop of the killing fluid on the eel upon the slide. It would be useless to 

 attempt to sec it under the high power during its time of active movement, 

 but it will soon become quiet enough for easy study. Do this with the high 

 power first, covering the object with a cover-glass, and then running enough 

 of the alcohol under the cover to entirely fill the space between it and the 

 slide. The eel can now be examined at leisure. 



Examination will convince one quite soon that the creature is not one of 

 such simplicity as is implied by the popular expression, *■ there is nothing to 

 him,' but that he is very complex. First observe his shape — very long and 

 narrow, blunt at one end, and sharply pointed at the other. Referring from 

 him to a live one under a low power you can readily see that the creature 

 always moves about pushing the blunt end forward, and this as well as other 

 facts prove that his body has a head end, though .it exhibits nothing which 

 suggests a head separated by a neck from the body and bearing eyes or other 

 sense organs. If now the high power study be resumed the various parts 

 of this body can be distinguished, after very careful study, for the parts are 

 transparent, and hence difficult to see. At the blunt front end of the body a 

 notch marks the entrance to the digestive tube. The mouth can be seen 

 leading into a straight thick-walled gullet^ and this in turn into a globular 

 gizzard. From the gizzard a tube runs straight through the body, which 



