vi PREFACE. 



with the two chapters on Fixing and Hardening Agents, thus 

 saving much unnecessary repetition. And on the other hand 

 there has been added a great deal of new explanatory matter 

 concerning such subjects as the theory of fixation, microtome 

 knives and knife-position, serial section methods, and the like : 

 the chapter on Cytological Methods has been for the most 

 part rewritten : and throughout Part II numerous new 

 examples have taken the place of former ones, or have been 

 added to them. 



The amount of new matter thus brought into the book is 

 very considerable ; but notwithstanding this the size of the 

 volume has not been increased, and I venture to hope that the 

 reader will find that the labour that has been expended on it 

 has not been expended in vain. 



COLOGNY, GENEVA, SWITZERLAND; 

 May, 1900. 



