450 SUMMARY OF CUERENT RESEARCHES RELATING TO 



membranes, the choroid plexus, &c., which can never be done without 

 extensive injury to the specimen, often rendering impossible the 

 preservation of the structure of its most delicate parts or, in patho- 

 logical preparations, preventing the full presentation of the morbid 

 appearances. In the majority of cases a most important link in the 

 chain of pathological evidence may thus be lost. 



The sections, even of the largest size, are handled, without 

 difficulty or danger of becoming torn, by floating them (in the basin, 

 filled with alcohol in which they were cut), with a fine camel's-hair 

 pencil on sheets of glazed writing-paper, to which they will not 

 adhere as long as the paper is ke2)t wet. They will adhere sufficiently 

 however, to be easily removed when the paper is slowly raised by one 

 corner. They are thus transferred with the paper, which is at once 

 numbered and marked, as desired for storing them away or into the 

 staining fluid, the washing or the fixing fluid, &c., and the oil for 

 clearing them up. From thence, when placed on the mounting slide, 

 the sheet of paper can easily be pulled oft', which can be done without 

 injuring the delicate ej)ecimen in the least. It is then advisable to 

 pi;t all parts of the section in their proper position and to remove all 

 foreign material visible to the eye, aided by a low magnifying lens. 

 After most of the oil has been removed by placing the slide gradually, 

 for a short time, in a vertical position, the section will adhere so 

 firmly to the glass surface that the mounting fluid can be poured on 

 it and the cover adjusted without displacing any of its parts. It is 

 necessary, however, to remove at once, and as quickly as possible, by 

 the use of blotting-paper, any surplus of mounting fluid, and to drive 

 out all air-bubbles by gentle stroking pressure on the cover-glass 

 from the centre towards the periphery. 



The sections are j^referably mounted in balsam, diluted with 

 chloroform or benzole, on plate-glass slips 5 in. by 7 in., and 6 in. by 

 8 in. and 10 in., and with proper care no more difficulty from air- 

 bubbles is found with these than with the ordinary slides. 



To harden the entire brain so that the inside and the outside shall 

 be hardened equally and properly, Dr. Deecke finally adopted bichro- 

 mate of ammonia in ^ to 1 per cent, solution, according to the 

 consistence of the brain. When nominally soft he adds say l-6th to 

 1-lOth per cent, of chromic acid to the solution, and always l-6th to 

 l-4th of the whole volume of alcohol. It is then placed in a 

 refrigerator and the fluid changed frequently. After a month add a 

 little more alcohol from week to week until the alcohol is 90 per 

 cent, This is changed as often as it is discoloured. The treatment 

 requires from 12 to 18 months. 



Schulze's Section-stretcher.* — Dr. F. E. Schulze holds down the 

 section whilst it is being cut, preventing it from rolling up, by means 

 of a small weight, shown in fig. 87. This weight, which is about 

 8 mm. long and rounded at the ends, is attached to a small steel rod. 

 The rod passes through a tube, so that it can easily be turned within 

 it, and slipped up or down. To this tube is soldered a thin watch- 



* Zool. Anzeig., vi. (1883) pp. 100-3 (1 fig). 



