36 INTRODUCTION. 



and organization. Ifor are the revelations of the one less sur- 

 prising to those who find their greatest charm in novelty, or less 

 interesting to those who apply themselves to the study of their 

 scientific bearings, than are those of the other. The universe 

 which the Microscope brings under our ken, seems as unbounded 

 in its limit as that whose remotest depths the Telescope still 

 vainly attempts to fathom. "Wonders as great are disclosed in a 

 speck of whose minuteness the mind can scarcely form any dis- 

 tinct conception, as in the most mysterious of those nebulse whose 

 incalculable distance bafiles our hopes of attaining a more inti- 

 mate knowledge of their constitution. And the general doctrines 

 to which the labors of Microscopists are manifestly tending, in 

 regard to the laws of Organization and the nature of Vital Action, 

 seem fully deserving to take rank in comprehensiveness and im- 

 portance with the highest principles yet attained in Physical or 

 Chemical Science. 



As the primary object of this treatise is to promote the use of 

 the Microscope, by explaining its construction, by instructing 

 the learner in the best methods of employing it, and by pointing 

 out the principal directions in which these may be turned to 

 good account, any detailed review of its history would be mis- 

 placed. It will sutfice to state, that whilst the simple microscope 

 or magnifying-glass was known at a very remote period, the 

 compound microscope, — the powers of which, like those of the 

 telescope, depend upon the combination of two or more lenses, — 

 was not invented until about the end of the sixteenth century ; 

 the earlier microscopes having been little else than modified tele- 

 scopes, and the essential distinction between the two not having 

 been at first appreciated. Still, even in the very imperfect form 

 which the instrument originally possessed, the attention of scien- 

 tific men was early attracted to the Microscope ; for it opened to 

 them a field of research altogether new, and promised to add 

 largely to their information concerning the structure of every 

 kind of organized body. The Transactions of the Royal Society 

 contain the most striking evidence of the interest taken in mi- 

 croscopic investigations two centuries ago. Their early volumes, 

 as Mr. Quekett truly remarks, " literally teem" with improve- 

 ments in the construction of the Microscope, and with discoveries 

 made ,by its means. The Micrographia of Robert Hooke, pub- 

 lished in 1667, was, for its time, a most wonderful production ; 

 but this was soon surpassed by the researches of Leeuwenhoek, 

 whose name first appears in the Philosophical Transactions, in 

 the year 1673. That with such imperfect instruments at his 

 command, this accurate and pains-taking observer should have 

 seen sq much and so well, as to make it dangerous for any one 

 even now to announce a discovery, without bavin o- first con- 

 sulted his works, in order to see whether some anticipation of it 

 may not be found there, must ever remain a marvel to the micro- 

 scopist. This is partly to be explained by the fact, that he 



