52 PROCURING OBJECTS. 



once subjected to examination. When it is desirable to examine the 

 contents of different infusions, the feeding pin should be washed in 

 distilled water between each dip, to prevent mixing. An infusion of 

 common black pepper and of the red cabbage, if left exposed to the 

 air for a few days, are excellent media for the production of ani- 

 malcules. 



51 There are some animalcules, to procure which requires greater 

 care and more trouble ; such, for example, are the eels in paste. The 

 following is the readiest method of obtaining these. Boil a little - 

 flour and water till it comes to the consistence of such a paste as is 

 used by bookbinders or shoemakers. This paste should be made from 

 flour and water only ; that of the shops, containing resin and other mat- 

 ters, is unfit for the purpose. Expose it to the air in an open vessel, 

 and beat it from time to time with a wooden spatula, to prevent its sur- 

 face becoming hard or mouldy. After a few days, particularly when 

 the weather is warm, it will turn sour. Then if it be examined with 

 attention, myriads of eels will be found on the surface. When they are 

 once obtained, their motion on the surface of the paste will prevent any 

 mildew, and it therefore requires no further attention. In like manner 

 it will prevent its freezing in winter. If the paste be too thin, they 

 will creep up the sides. In this case, a portion of very thick paste 

 must be added to preserve them. When it is desirable to give them a 

 fresh supply of food, it must not be put upon them, but they must be 

 placed upon it. 



To prepare them for the microscope take a' few drops of clean 

 water, and put a very small portion of the paste containing the eels 

 into it. After it has stood a minute or two, the eels may be taken out 

 and placed under the microscope, freed from a considerable portion of 

 foreign matter. 



52. WHEEL ANIMALCULE. The Vorticella Rotatoria, or Wheel 

 Animalcule, is another most interesting object for the microscope. In 

 many works directions are given to search for them in leaden gutters, 

 but the search of the microscopist in such situations will rarely be suc- 

 cessful. The best method of raising and preserving them is as follows. 

 Early in the spring fill a three-gallon jug with pure rain water, (not butt 

 water, for the larvae of the gnat tribe will then be mingled with them.) 



