38 GENERAL, HISTORY OF 



very minute mechanical division. The bodies generally 

 used are those of carmine, indigo, and sap-green, the first 

 being preferable. This material should be as pure as 

 possible. Take a piece or cake of it, and rub the corner 

 once or twice on the stage-glass, or what perhaps is better, 

 the lower plate of an aquatic live-box, having first moist- 

 ened it with a drop of water. The colouring requisite 

 for the purpose is very small only just sufficient to 

 render it appreciable to the naked eye for if there be 

 too much, the probability is, that the particles will be too 

 large for the creatures to imbibe. Having thus prepared 

 the coloured food, place a drop of it beside a drop of the 

 water containing the animalcules, but not so that they 

 may come into contact ; then put on gently the cover of 

 the live-box, and lower it sufficiently to flatten the two 

 drops of fluid, but not to force them to unite. Now 

 place the live-box under the microscope, and examine the 

 animalcules as closely as you can, and especially so as to 

 ascertain that their stomachs are colourless; then press 

 down the cover until the drops of fluid intermix, which 

 may be done under the microscope, and you will imme- 

 diately perceive the creatures in great activity, and readily 

 distinguish the cilia, proboscides, and other organs, of those 

 which possess them, and in a few seconds their stomachs 

 will be filled with the coloured substance. Some animal- 

 cules, however, take a considerable time to effect this, but 

 it is an exception to the general rule. 



