METHODS OF INVESTIGA TION. 1 1 ^ 



only remains to add the material to be examined and to fill the reservoir 

 with water. The water from the reservoir soaking through the bibulous 

 paper keeps the air-tight chamber constantly moist, and evaporating faster 

 from its contained free circular edge, prevents loss of moisture from beneath 

 the covering glass. The water in the reservoir will maintain the moist 

 chamber in the above conditions for many days and will require replenish- 

 ing only at distant intervals. 



Where uninterrupted observation is not demanded, but simply the 

 chronicling of the more important developmental phases of some sedentary 

 or encysted type, and where in the interim the microscope is probably 

 required for the examination of other objects, it will be found convenient 

 to transfer the slides containing the animalcules to an ordinary moist 

 chamber which may be extemporized out of a tumbler or small bell-glass 

 inverted upon a plate containing a few folds of well-saturated bibulous 

 paper. By a registration with a graduated scale on the mechanical stage, 

 or by a rough drawing of the bearings of the type to be re-examined with 

 relation to surrounding objects, it may be with facility refound for sub- 

 sequent observation. An efficient moist chamber for the same purpose, 

 and, as is often needed, for the transfer of a slide containing living Infusoria 

 from place to place, is ready to hand in the shape of an ordinary wide- 

 mouthed pomatum bottle, with some moistened blotting-paper at the 

 bottom ; the height inside being a little over three inches allows the cork to 

 be thrust down upon the slide, thus keeping it firmly in one position. 



The ingenious chambers constructed by Professor Tyndall for the 

 reception of test-tubes in connection with his experiments on atmospheric 

 germs, fully described in the succeeding chapter, and illustrated side by side 

 with Messrs. Dallinger and Drysdale's apparatus, at PL L., offer special 

 facilities for the effectual isolation and continued examination of specific 

 infusorial types. 



