98 The Mickoscope. 



to be cut. A brush having long hairs should be selected, for if the 

 hairs be short they are likely to be cut by the knife. For most 

 sections a small round brush is to be used, but if the sections are 

 large, a fiat brush, wide enough to cover the sections, is to be pre- 

 ferred. Having adjusted the brush, the knife is jDassed between it 

 and the rod, and the cut is made toward the operator, under the 

 Ijrush, when the section will be found lying perfectly ilat upon the 

 knife. 



The thinnest and most delicate sections are not injured by this 

 method. The tendency of sections to curl can also be obviated by 

 using paraffines of diflPerent melting grades, using hard in higher 

 and soft in lower temperature : or Iw varying the thickness of the 

 sections. 



Both of these methods are, however, open to objection. It is 

 extremely difficult to keep a room at a certain constant temperature, 

 that temperature which corresponds to the grade of paraffine 

 selected. Should the temperature of the room go down the sections 

 will cm-1, while if it rises, as is very apt to happen in warm weather, 

 the paraffine will become soft, and the sections will be hopelessly 

 torn. Then, too, a paraffine suitable to the room temperature is not 

 always best for the special object to be cut, and it has been my 

 exi)erience that the harder paraffines yield better results than the 

 softer. They allow the cutting of thinner sections without tearing. 

 As to varying the thiclmess of the sections, this is to be avoided, for 

 in histological or pathological work, the thinner the section the" 

 better, and it is the thinnest and most desirable section which curls 

 the most hopelessly. 



For these reasons a harder paraffine, together with a section 

 tlattener, is to be preferred, and by the aid of the simple apparatus 

 described the most delicate sections can be cut without either curl- 

 ing or tearini;. 



NO EXCESS OF BALSAM NECESSARY. 



JAMES E. WHITNEY, F. R. M. S. 



^ I "" HE clearing away of a mass of hard balsam from around the 

 -1- edges of a cover glass, is a very disagreeable occupation to 

 anyone, and is a task which, in the hands of a beginner, usually 

 results in a ruined slide, and a very much damaged temper. Per- 

 sonal observation shows that there are a good many experienced 

 workers who leave their slides in a very unsightly condition, on 

 account of the difficulty they find in removing the excess of balsam, 



