Vlll PREFACE. 



express purpose of making the comparison. Even among the 

 products of English skill, it was necessary for him to make a 

 selection ; and he trusts that he will be found to have done ade- 

 quate justice to all those who have most claim to an honorable 

 mention. 



The great objection to English Microscopes, especially on the 

 western side of the Atlantic, seems to be their costliness ; and 

 as it can be affirmed with truth, that the instruments of Nachet, 

 Oberhauser, and other Continental makers, are adequate for all 

 essential purposes, a general preference is given to the latter (as 

 the Author understands) among the Microscopists of the United 

 States. He feels sure, however, that no one who has ever been 

 accustomed to work with a well- constructed English Microscope 

 will ever give the preference to a foreign instrument ; and he is 

 glad to be able to announce that one of the best London firms 

 is now prepared to supply a Microscope of excellent quality at a 

 price very little exceeding that paid for Continental instruments, 

 of far superior capabilities. (See p. 103, note.) 



In treating of the Applications of the Microscope, the Author 

 has constantly endeavored to meet the wants of those who come 

 to the study of the minute forms of Animal and Vegetable life 

 with little or no previous scientific preparation, but who desire 

 to gain something more than a mere sight of the objects to which 

 their observation may be directed. Some of these may perhaps 

 object to the general tone of his work as too highly pitched, and 

 may think that he might have rendered his descriptions simpler 

 by employing fewer scientific terms. But he would reply to 

 such, that he has had much opportunity of observing, among 

 the votaries of the Microscope, a desire for such information as 

 he has attempted to convey (of the extent of which desire, the 

 success of the " Quarterly Journal of Microscopical Science" is a 

 very gratifying evidence) ; and that the use of scientific terms 

 cannot be dispensed with, since there are no others in which the 

 facts can be expressed. As he has made a point of explaining 

 these, in the places where they are first introduced, he cannot 

 think that any of his readers need find much difficulty in appre- 

 hending their meaning. 



The proportion of space allotted to the various departments, 

 has been determined, not so much by their Physiological im- 

 portance, as by their special interest to the Microscopist ; and 

 the remembrance of this consideration will serve to account for 



