10 PREFACE. 



furnished with a brief sketch of the uses of the 

 microscope, and its various improvements. This 

 appeared to be preferable to commencing- with the 

 original Exordium, on account of the progress 

 microscopic science has made in public opinion, and 

 the enlarged view which is now taken with respect 

 to the microscope. As, however, there are many 

 persons who desire and expect to meet with the 

 Exordium in the present edition of this work, it 

 has been deemed advisable to give it entire in the 

 Appendix, with Dr. Goring's corrections. 



The three succeeding chapters are appropriated 

 to a description of certain living microscopic objects; 

 and containing, as they do, some remarkable parti- 

 culars relating to the wonderful metamorphoses 

 which these creatures are ordained to undergo, it 

 is confidently hoped they will not be deficient in 

 interest or instruction. 



The remaining portion of the volume contains an 

 account of the mechanical construction of the micro- 

 scope and its apparatus; and since we have no 

 other work devoted to this branch of the subject, 

 affording to all persons possessing this instrument 

 such practical instructions as are absolutely neces- 



