INTRODUCTION. XV 



help the beginner to ascertain the names and a little 

 of the structure of a few of the common microscopic 

 creatures, both animal and vegetable, with which the 

 fresh waters of the land are filled, "and it tries to do so 

 in the simplest and most direct way, leaping scientific 

 hedges and trampling on scientific classification in a 

 manner that will dismay the learned botanist and zo- 

 ologist. But the botanist and zoologist have weighty 

 books that delight their soulp, so why should not the 

 beginner with a microscope have a book to help him if 

 to nothing more than to the names of the commonest 

 aquatic objects, and, it is hoped, delight him by 

 smoothing the path that leads to them ? The writer 

 will not be greatly troubled if the learned botanist and 

 zoologist do not like this little book, provided the be- 

 ginner in the use of the microscope approve it and 

 find it helpful. 



It relates almost exclusively to aquatic objects. 

 One reason for this has already been mentioned; An- 

 other and more potent one is, that even the beginner 

 knows, in a general way, what he is looking at when 

 he magnifies the common objects of the land, but the 

 microscopic creatures from the water are so truly mi- 

 croscopic, the observer must so often go fishing on 

 faith, and only know the contents of his net by faith 

 and imagination until he can examine his collection 

 drop by drop with the microscope, that he is lost at 

 the start unless he has a book to help him, which this 

 one hopes to do. 



But is it necessary to say that the following pages 

 do not contain notices of everything to be found in 

 the ponds and ditches ? The beginner will capture 

 many objects which he will not find described here. 



