LOCALITIES or INFUSORIA, ETC. 395 



the localities above described, tried several other plans for the 

 purpose ; but the following he recommends as the best :* — 

 " Early in the spring he fiUs a three-gallon jug with pure 

 rain-water (not butt-water, because it contains the larvae of 

 gnats), from this he takes a sufficient quantity, nearly to 

 fill a half-pint jug, he then ties up a small portion of hay 

 or green sage leaves into a bundle, and places the same 

 in the mug; about every ten days he removes all the 

 ■decayed portions with a piece of wire, and substitutes a 

 . fresh supply ; a little of the deposit scraped from the side 

 of the mug near the surface, when placed under the micro- 

 scope, will be certain to exhibit them. As the water evapo- 

 rates from the mug, the excess of rain-water in the large vessel 

 wiU supply the deficiency. The sage leaves were found 

 to produce the largest numbers. The same mug," Capt. Ford 

 also states, " for the seven years preceding the date of his note 

 (in 1841), had never failed to yield an abundance." If the 

 animalcules be kept in glass bottles, they should not be 

 exposed to a direct light ; in a room they may be placed in a 

 dark corner, or upon a table between two windows, so long as 

 the light that is allowed to fall on them is difiused ; they will 

 then thrive very rapidly. 



Method of Feeding Infusoria with Carmine. — In order to 

 display the currents made by the cUia of these minute animals, 

 as well as to exhibit the form of the digestive system, a certain 

 amount of colouring matter introduced into the water con- 

 taining them wiU render both more evident. This plan was 

 first employed by M. Trembley, without any important 

 result, but Ehrenberg followed it up more carefully, and was 

 led to the discovery of the internal structure of those infusoria 

 which he subsequently termed Polygastria. 



The method of proceeding is to rub some pure sap-green, 

 indigo, or carmine upon a palette or a plate of glass, and add 

 to this a few drops of water ; if the glass be now held on one 

 side, a portion of the water containing a certain amount of the 

 colouring matter may be dropped upon the tablet of an 

 animalcule cage, or into the water in which the animalcules 

 * Microscopical Jommal, vol. i.,' p. 96. 



