COLLECTING 527 



be fitted into cases, to avoid the risk of breakage. When animalcules 

 are being collected, the bottles should not be above two-thirds 

 filled, so that adequate air-space may be left. Whilst engaged in 

 the search for microscopic objects, it is desirable for the collector to 

 possess a means of at once recognising the forms which he may 

 gather, where this is possible, in order that he may decide whether the 

 ' gathering ' is or is not worth preserving ; and for this purpose we know 

 of nothing better, unless a small travelling microscope be required, than 

 a couple of Steinheil loups, magnifying six and ten diameters. 



Mr. J. D. Hardy suggests what we have found of great use, viz. 

 aflat bottle, as a very valuable piece of apparatus for collecting. 1 It is 

 made by cutting a Lj -shaped piece out of a flat and solid piece of india- 

 rubber, about 6 inches long by 2| inches broad, and j inch thick ; 

 against each side is cemented (by means of Miller's caoutchouc 

 cement) a piece of good thin plate-glass, and the bottle is complete. 

 A small portion cut from the inner piece makes a naturally fitting 

 cork. One or two more, and smaller, bottles can be made with the 

 remaining indiarubber. It is essential that the material should be 

 at least J inch thick in order to make a wide bottle, and allow pond- 

 weeds to be put inside without difficulty and pressure. A flat bottle is 

 made by Mr. Stanley, London Bridge, which we have good reason to 

 write favourably of. It is ground on its outer surfaces, and internal 

 irregularities almost wholly disappear when filled with water ; an 

 objective from 3 inches to 1^ inch may be well employed with it. 



Even with the best ordinary round dipping bottles it is very 

 difficult to see minute animals clearly, whilst with this flat bottle 

 one can see at a glance almost everything the dip contains, and 

 every object can be examined with the pocket lens with ease. 



For collecting purposes the objects sought in pond or stream are 

 divisible into free -swimming, and attached or fixed to water-plants, &c. 



The free-swimming are to be secured with the net, the bottle 

 attached to which should be examined after each sweep of the net ; 

 and the flat bottle may be also filled for examination. The mud at 

 the bottom of the pond must not be stirred by the net, since of 

 course it obscures the objects. 



The infusoria, rotifera, &c., are best found with the flat bottle. 

 Collect a lot of the ' weeds ' growing in pond or stream, and place 

 these in the bottle ; then, Mr. Rousselet says : ' The tree-like colo- 

 nies of Yorticellae ; Epistylis, Zoothamium, and Carchesium, the 

 trumpet-shaped Stentors, the crown Rotifer Stephanoceros, the 

 tubes of Melicerta, Lymnias, the various Polyzoa, also Hydra, 

 and many more, can at once be seen with the naked eye, when 

 present, and in this way the good branches can be selected. Some 

 creatures, however, such as the beautiful floscules, cannot be seen 

 easily, even with the lens, not so much on account of their small 

 size, as of the perfect transparency of their bodies. Experience 

 will soon teach one how to see which branches are likely to prove 

 prolific. As a general rule, old-looking but still sound and green 

 branches will be the best. The Water Milfoil (Myriophyllum) is 

 decidedly the best of water plants to examine and collect, on account 

 1 Q.M. Journ. ser. ii. vol. ii. p. 55. 



