GENERAL METHODS. 31 



the rotation of the balance-wheel by hand power or by a 



water motor, and its work is thus more uniform and more 



rapid than that of the sledge 



microtomes of the Schanze and 



Thoma types. It is not suited 



for cutting objects in celloi- FIG I5 ._ Mlcrotome knife After 



^in.*] Henking. 



Of the many microtome knives used I have found most 

 suitable that recommended by Henking (I) with a very short 

 edgef(cf. Fig. 15). 



I must particularly describe the imbedding of objects to 

 be cut and the manipulation of microtome sections, espe- 

 cially their attachment to the slides. But it cannot be my 

 duty to bring together the very numerous methods recom- 

 mended by various authors. It will be better for me to 

 confine myself to the careful description of a few methods 

 whose trustworthiness I have had opportunity to prove. 

 Therefore I will particularly describe, among the various 

 modes of imbedding, only the paraffine method, which is by 

 far the best adapted to vegetable objects. 



I. Imbedding in Paraffine. 



43. For imbedding in paraffine, objects stained in mass or 

 unstained objects may be used. If one is concerned with 

 protoplasmic structures, these must, of course, be carefully 

 fixed and the fixing medium must be washed out before 

 imbedding. 



The size of the pieces to be imbedded depends naturally 

 upon the nature of the object. In general it is advantageoos 

 to use as small pieces as possible, for, on one hand, these 

 are more easily penetrated by the various fluids, and, on the 



* [This microtome is sold by the Franklin Educational Co., Hamilton PI., 

 Boston, at $60, with knife.] 



f These are to be obtained of W. Walb (Heidelberg, Hauptstr. 5) under 

 the name of " Henking's microtome knife," at the price of Mk. 4.50 ($1.10) 

 -each. 



