SECTION ONE 



4. 95% aqueous T.B.A. for 1-3 hours. 



5. Pure T.B.A. for 3 changes of 4 hours in each. 



6. Equal parts of Uquid paraffin and T.B.A. for 1-2 hours. 



7. Infihrate in paraffin wax. 



CAJEPUT OIL 

 For clearing 



Phis reagent will absorb small amounts of water without cloud- 

 ing, and it is, therefore, particularly useful in wet climates as a 

 clearing agent in place of xylol. Cajeput oil is considerably more 

 expensive than xylol, however. 



CELLOSOLVE 

 (Ethylene glycol monethyl ether) 



For dehydrating thin slices of tissue and sections 



This reagent, which is a colourless, inflammable liquid, mis- 

 cible with water, alcohol, xylol, cedarwood oil, clove oil, and 

 various other oils and solvents, and is also a good solvent for 

 many stains, is coming into increasing use both for animal and 

 plant histology, in place of ethyl alcohol : in fact many laboratories 

 in Great Britain, at least, employ cellosolve in preference to the 

 ethyl alcohol technique, which they now regard as obsolete. 

 However, although some workers believe cellosolve to be superior 

 to all other dehydrating agents as it obviates hardening and dis- 

 tortion of most tissues, it is unsuitable for bulk material as it tends 

 to cause distortion of protoplasmic cells owing to the rapidity of 

 its dehydrating action. 



Technique : 



1. Wash pieces of tissue, not more than 5 mm. thick and im- 

 merse directly into cellosolve for half an hour. 



2. Immerse in a fresh bath of cellosolve for half to one hour. 



3. Immerse in a third bath of cellosolve for the same time. 



4. Complete the dehydration in a fourth bath of cellosolve for 

 an hour-and-a-half. 



35 



