X PREFACE. 



opportunity of acknowledging the kind assistance afforded him 

 on all occasions by Messrs. Powell and Lealand, Mr. Koss, 

 and Messrs. Smith and Beck. He would here, also, beg to 

 tender his best thanks to Dr. Pereira, Mr. Bowerbank, Mr. 

 Jackson, and other gentlemen, who have obligingly aided him 

 with much useful information during the progress of the book, 

 as well as to the artists, Messrs. Leonard and Aldous, and 

 the wood engravers, Messrs. Vasey and Joyce, for the able 

 manner in which their part of the work has been executed. 



In conclusion, the Author trusts that his endeavours may 

 not be unavailing in affording assistance to those who are 

 engaged in Microscopic investigations; and should his efforts 

 be conducive, in the slightest degree, to the promotion of 

 scientific research, the end for which he has laboured will be 

 fuUy accomplished. 



15, DOKOHESTEK PlaOE, 



Blandfokd Square, 



Nov. nth, 1848. 



