PREFACE, 



4 



IN the spring of 1834 the Natural History of Animal- 

 cules was published. The design of that work may be 

 seen in the following extract from its pages : 



" Where can you refer me to a description of Animal- 

 cules ? What magnifying powers are the best to view them 

 with ? What are their comparative sizes ? I have found 

 a very curious creature, of such and such a form, is it 

 known ? Where can I obtain drawings of such as are 



known ? &c. &c. I have ventured to take a general sur- 







vey of the subject, and the more willingly, because at 

 present no similar work exists, unless it be that of Adams, 

 published in 1787* which contains only a very slight ac- 

 count of the external characters of such as were known in 

 his time, without giving any admeasurement of their size, 

 or sufficient figures to render it generally useful ; while its 

 price is such as to place it beyond the reach of many 

 persons." 



The Natural History of Animalcules is now out of print; 

 a Second Edition would have appeared, but the favourable 

 reception of the first has induced me to prepare, at consi- 

 derable expense, the present manual, conceiving greater 



