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PEBFACE. 





In the spring of 1834 the Natural History of Animalcules 

 was pubUshed. The design af that work may be seen in 

 the following extract from its pages : — 



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

 malcules ? 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 survey of the subject, and the more wil- 

 lingly, because at present no similar work exists, unless 

 it be that of Adams, published in 1787> which con- 

 tains 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." 



The Natural History of Animalcules is now out of 

 print; a Second Edition would have appeared, but the 



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