SECTION THREE 



Solutions required: 

 Note: Solutions A and B each contain 20% of Nitrocellulose: 



A. Absolute alcohol . . . . 210 ml. 



Ether . . . . . . . , 250 ml. 



Dibutyl phthalate . . . . 5 ml.* 



Mix well and add 140 gm. L.V.N, (as supplied 

 damped with N. butyl alcohol). 



B. Absolute alcohol . , . . 210 ml. 

 Ether . . . . . . . . 250 ml. 



Mix well and add 140 gm. L.V.N, (damped with 

 N. butyl alcohol). 



From Solution B prepare also 5% and 10% solutions by diluting 

 with a mixture consisting of equal parts of absolute alcohol and 

 ether. 



C. Xylol . . . . . . . . 2 parts 



Toluol . . . . . , . . I part 



Beechwood creosote . . . . i part 



Procedure for embedding tissues: 



1. Fix and dehydrate tissues as usual; then immerse in ether- 

 absolute alcohol (equal parts) for one day. 



2. Immerse in 5% L.V.N, for three to five days. 



3. Transfer to 10% L.V.N, for one to two days. 



4. Transfer to 20% L.V.N. (Solution B above) for one to five 

 days. 



5. Embed in Solution A. 



* Note: In the original paper (Chesterman &; Leach, 1949) and in E. Gurr 

 (1950a, 1953), tricresyl phosphate was stipulated: this has now been replaced 

 by dibutyl phthalate, and thanks are due to Professor F. Bergel of The Chester 

 Beatty Research Institute, Institute of Cancer Research, Royal Cancer Hospital, 

 London, for calling attention to the potential danger of handling tricresyl 

 phosphate. Professor Bergel states that tricresyl-o-phosphate is highly toxic, 

 more than 7-30 mg./kg. producing severe paralysis, and while the correspond- 

 ing meta- and para-compounds show little sign of having this toxicity, the 

 tricresyl phosphates on the market, up to the present time, always contain some 

 of the ortho compound. 



References : 



Aldridge, W. N. (1954). 



Thompson, R. H. S. (1954). 



Martindales Extra Pharmac. (1941), vol. i, 200-201. 



495 



