ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 531 



cytological methods, having been rewritten. The amount of new matter 

 added is very considerable ; and these additions, in order to keep within 

 the limits of the old size, have necessitated severe condensation of the 

 text and the rejection of superfluous methods. More space has been 

 given to the principles of some of the methods described, and there is 

 much additional information respecting the theory of fixation, microtome 

 knives, serial section methods, and the like. The general features of this 

 invaluable work are so well known that it is unnecessary to sketch them 

 out again. 



