METHOD OP OBTAINING INFUSORIA, ETC. 387 



A tin box, h, fig. 252, containing six or twelve short glass 

 tubes, provided either with plain corks, or with corks through 

 which a piece of glass tube or quiU has been passed in the 

 manner shown at i, will be found very convenient for aU the 

 smaller kinds of infusoria. 



The fishing tubes have already been described at page 133 ; 

 these will be useful for separating the large voracious animals 

 from the more delicate ones. 



The pocket magnifier may be of either of the forms shown 

 by figs. 23 and 24, or the Coddington lens, represented by 

 fig. 26, when the infusoria are very minute. Dr. Arthur Farre 

 has lately shown the author a convenient form of lens, which 

 he finds very useful for most of the marine Polypes; this 

 consists of two double-convex lenses of difierent focal lengths, 

 placed in a setting with an ebony stop between them, some- 

 what in shape like an hour-glass. This lens performs like a 

 doublet or Coddington, and, although of long focus, magnifies 

 considerably. 



Method of Obtaining Infusoria. — In order to be successful 

 in the capture of these minute creatures, a knowledge of their 

 habits must be first acquired, and upon this matter, as well 

 as upon the method of cultivating Chara, ValKsneria, &c., 

 the author is indebted to Mr. Varley for many valuable 

 instructions. 



" The tendency of all Infusoria," says Mr. Varley, in a letter 

 to the author, " is towards the light, and also to the surface ; a 

 filmy surface will hold many. On arriving at a pond, it wiU 

 be noticed that the ' off side,' or that towards which the wind 

 is blowing, wiU be coated with scum, whilst the ' near side ' will 

 be bright ; these sides wiU differ materiaUy in the quantity of 

 animalcules they may contain, the bright side being often 

 without any ; if the wind blows towards the sunny side, that 

 side will be especially prolific. Shallow parts being warmer 

 than deep, will also yield a more abundant supply." 



" The rod with the phial attached, as shown in fig. 252, is 



to be carried into the water in such a manner that the phial 



may be kept in an inverted position, and when arrived at the 



proper depth the rod is to be turned, and the mouth of the 



25* 



