GENERAL 'METHODS. 37 



necessary to set the knife very slightly oblique, and as 

 nearly as possible parallel, to the direction of its motion, so 

 that the celloidin shall be cut with a long drawing stroke. 

 The knife and the top of the block should also be kept wet r 

 during cutting, with alcohol of the strength of that in which 

 the block was hardened. With these precautions excellent 

 sections may be obtained. 



Busse (I) recommends the use of photoxylin instead of 

 celloidin, as it gives a more completely transparent imbed- 

 ding mass. The* details of its manipulation are precisely 

 the same as for celloidin. More detailed accounts of the 

 use of celloidin may be found in papers by Eyclesheimer 

 (I) and Koch (I).] 



2. The Attachment of Sections. 



50. For the purpose of dissolving out the paraffine from 

 microtome sections filled with it, these are commonly at- 

 tached to the slide. Although recently a large number of 

 methods for accomplishing this have been proposed, I will 

 restrict myself to describing somewhat in detail four of 

 them, each of which seems to possess certain advantages 

 for some cases. 



A. ATTACHMENT WITH COLLODION. 



In the first of these a solution of about 5$ of officinal 

 collodion* is used for attachment. It is conveniently kept 

 in a bottle having a soft brush inserted through its cork. A 

 drop of this solution is first allowed to flow under the sec- 

 tions arranged as desired on a slide, a piece of filter-paper 

 is then laid upon them, and the sections are pressed down 

 upon the slide with the finger or with a paper-knife or simi- 

 lar instrument. Then the sections are painted over with 

 the collodion solution and it is allowed to dry in the air. 

 When this is done, the slide is warmed over a small flame 



* [Or a mixture of equal parts of a thin solution of collodion and clove-oil.} 



