BINOCULAR MICROSCOPE AND A LIVE BOX. 177 



do it, it is also possible to get a rotifer in so small a drop of water 

 that it is unable to swim out of the field of view of a quarter inch 

 objective. I have had it in constant use for animals of all sizes, from 

 the smallest infusoria to tadpoles, and I hope it will be found equally 

 useful to my fellow pond-hunters. 



I have also a small screw compressor, made on the same prin- 

 ciple ; it is very simple, and effective, and allows of regulating the 

 pressure to a nicety. 



