iv Preface. 



The number of objects enumerated is so great, that 

 only a brief space could be assigned to each, except by 

 increasing the size and price of the volume. It has been 

 my desire not to come into competition with any other 

 book for the Microscope, and I hope that I have suc- 

 ceeded. In selecting objects for enumeration, I have 

 endeavoured to confine myself to those that are common 

 and easily examined, excluding all sections, injections, or 

 preparations requiring an experienced hand. 



To all who have aided me with drawings, suggestions, 

 or assistance in any form my thanks are due ; and, if 

 these pages should induce but a few readers to appeal to 

 works of greater pretensions, our labour will not have 

 been altogether in vain. 



M. C. COOKE. 



