PREFACE. Vll 



the structure of Insects, and the Primary Tissues of Vertebrata), 

 in order that he might give more space to those on which no such 

 sources of information are readily accessible. For the same 

 reason, he has omitted all reference to the applications of the 

 Microscope to Pathological inquiry ; a subject which would inte- 

 rest only one division of his readers, and on which it would have 

 been impossible for him to compress, within a sufficiently -narrow 

 compass, a really -useful summary of what such readers can readily 

 learn elsewhere. So, again, the application of the Microscope to 

 the detection of Adulterations in Food, &c. , is a topic of such a 

 purely-special character, and must be so entirely based on detailed 

 descriptions of the substances in question, that he has thought it 

 better to leave this also untouched. On the other hand, he has 

 gone somewhat into detail in regard to various forms of Vege- 

 table and Animal life, which the diligent Collector is not unlikely 

 to meet with, and which will fully reward his most attentive 

 scrutiny. 



It has been the Author's object throughout, to guide the possessor 

 of a Microscope to the intelligent study of any department of 

 Natural History, which his individual tastes may lead him to 

 follow-out, and his individual circumstances may give him facili- 

 ties for pursuing. And he has particularly aimed to show, under 

 each head, how small is the amount of reliable knowledge already 

 acquired, compared with that which remains to be attained by the 

 zealous and persevering student. Being satisfied that there is a 

 large quantity of valuable Microscope-power at present running to 

 waste in this country, — being applied in such desultory observa- 

 tions as are of no service whatever to Science, and of very little 

 to the mind of the observer, — he will consider himself well 

 rewarded for the pains he has bestowed on the production of this 

 Manual, if it should tend to direct this power to more systematic 

 labours, in those fertile fields which only await the diligent cul- 

 tivator to bear abundant fruit. 



In all that concerns the working of the Microscope, the Author 

 has mainly drawn upon his own experience, which dates-back 

 almost to the time when Achromatic Object-glasses were first con- 

 structed in this country. He would be ungrateful, however, if he 

 were not to acknowledge that he has derived many valuable hints 

 from the Practical Treatises of Mr. Quekett and Professor Beale, 

 and from the Micrographic Dictionary of Messrs. Griffith and 



