FROZEN SECTIONS 123 



Miller [op. cit.) stains usually in Hollande's chloro-carinine- 

 iron alum as follows : Hollande one minute. Rinse 30 per cent, 

 alcohol, then quickly through distilled water to 3-5 {)er cent, iron 

 alum, till black. Control under microscope. Wash in distilled 

 water, dip in 5 per cent, pyridine in distilled water. Wash in 

 distilled water. Transfer to running tap water for at least ten 

 minutes — then distilled water and upgrade and mount in balsam. 



230. For Cytological or Histological work of the best type, the 

 knife cooling attachment should be used. When the section is 

 two-thirds cut, place a dry, clean coverslip, held in a pair of 

 forceps, just where the section is curling up, and it will adhere 

 to the coverslip. By gently pulling knife and section on the cover- 

 slip towards you the whole section will thaw on to the surface of 

 the coverslip. The section may now be fixed immediately in 

 osmic or formalin vapour, and then be placed in the fixing fluid 

 desired. With gentle treatment such sections stick well to the 

 coverslips (or slides, if these be preferred) until finally stained and 

 mounted. It may be necessary to spread out the section on the 

 frozen knife with a dry camel-hair brush, before making it 

 adhere to a coverslip or slide, and finally finishing the sv/eep of the 

 knife. It is difficult to describe this process, but it is fairly easy 

 to master the trick of getting the sections on to the glass after 

 some practice. It should be remembered that sections must be 

 rolled out on the frozen knife and not on the slide, in those cases 

 where they curl badly. 



It may be mentioned that the development of this method is 

 due to Messrs. Leitz. It is a definite advance in microtomy. 



231. Gelatin Imbedding for Freezing Technique, refer to § 179, 

 which gives the recent method of Zwemer. 



232. Glychrogel Mounting Solution of Zwemer for Frozen 

 Sections, refer to § 474. 



