OF THE MICBOSCOPE. 135 



surface downwards, most objects of interest fall away from it, 

 and may be found in the water. A single bottle of this descrip- 

 tion is sufficient, as the cork is easily removed, so that the water 

 may be poured into other bottles. As ordinarily made and sold, 

 "Wright's collecting bottle is an expensive piece of apparatus, 

 costing four or five dollars, but as shown in the engraving it 

 may be made for a few cents by any tinsmith. 



Where it is desirable to keep the specimens thus obtained so 

 that they may be examined, and their life-history studied, 

 bottles and jars of almost any kind may be used, but those which 

 we have found most convenient are what are known as "quin- 

 ine " bottles, and may be had at most druggists. For ordinary 

 objects they are just about the right size, and as they are made 

 of tolerably clear glass it is easy to examine the objects through 

 the sides of the bottle. A dozen or two of these little aquaria 

 occupy very little space, and are easily handled. Great care 

 must in general be taken to exclude from the vessels contain- 

 ing the finer organisms, such predatory animalcules as devour 

 them. Water fleas, the larvae of insects, etc. , will soon make 

 away with the finer specimens. On this account great diffi- 

 culty is found in keeping the Volvox Globator, since it is greedily 

 devoured by various rotifers, and these are exceedingly difficult 

 to exclude. We have succeeded best in this case by partially 

 filling a bottle with well-filtered water taken from the same 

 pool as the specimens, and transferring the objects to it singly 

 so as to avoid transferring their enemies too. For this purpose 

 the dipping tube should be used. Some authors caution us 

 against mixing the inhabitants of different pools, on the ground 

 that being strangers to each other they will fight. This is more 

 fanciful than accurate, though it has a basis of truth. It is not 

 the circumstance that they are strangers that causes the diffi- 

 culty, but the fact that the one is the natural prey of the other. 

 The same thing occurs between inhabitants of the same pool. 

 It must be remembered, however, that very slight changes in 

 the conditions in which they are placed will often cause the de- 

 struction of these objects. Thus, we have seen some very fine 

 gatherings totally destroyed by being removed from soft, boggy 

 water to clear, hard well water. Therefore, in transferring 

 either animals or vegetables to an aquariun, it is well to supply 



