Vlll PREFACE. 



Henfrey. Almost every working Microscopist, however, has 

 methods and appliances of his own, which, having devised them 

 for his special ends, he prefers to all others : to have noticed any 

 considerable number of these (many of them described in recent 

 volumes of the " Quarterly Journal of Microscopical Science") would 

 have added too much to the bulk of his volume ; and the Author 

 has deemed it preferable to limit himself in most instances to 

 those which he has himself tried and found to be serviceable, — 

 his object being, not the impossible one of teaching his reader all 

 that has to be learned, but the putting him in the way of learning 

 it from that best of all teachers, Experience. 



The whole Treatise has been subjected to a most careful revision ; 

 and by the sacrifice of the Introduction and the transfer of 

 many of the Wood-cuts to separate Plates, room has been found 

 for additional matter amounting in the whole to nearly forty 

 pages, — the most important single additions being the account of 

 Eozoon Canadense (pp. 517-521), and the outline of Prof. Beale's 

 views on the Formation of the Elementary Tissues of Animals 

 (pp. 689-693). Everywhere the number of References to the most 

 valuable sources of more detailed information has been greatly 

 augmented ; and the number of Illustrations has again been 

 largely increased. 



University of London, 

 March, 1868. 



