PREFACE. 



Few branches of science hold out stronger induce- 

 ments for their study than the Natural History of 

 Animalcules^ which^ while it is pursued with great 

 facility, affords, at the same time, by reason of the 

 singular forms and diverting habits of these crea- 

 tures, a degree of interest scarcely to be exceeded. 

 For this reason, and to reply to the many inquiries 

 addressed to me, such as — Where can you refer me 

 to a description of animalcules? — What magnifying 

 powers are the best to view them with ? — What are 

 their comparative sizes ? — 1 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 account 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. 



