9 8 Neurological Technique 



A. Van Gehuchten s fluid. — 



Strong alcohol (absolute preferably), 6 parts. 



Chloroform, 3 parts. 



Acetic acid (glacial or concetitrated), i part. 



Use in a tightly closed vessel. 



After 6-24 hours of fixation in this fluid the specimen should 

 be transferred to 80 per cent, alcohol, or commercial alcohol 

 (95 per cent.) to which has been added about one-fourth its 

 volume of distilled water. In this it may remain indefinitely. 



B. Zenker's fluid. — 



To each 100 cc. of distilled water 

 add 5 g. of mercuric bichloride, 



5 cc. of acetic acid (glacial or cone), 

 2 g. of potassium bichromate. 



When first devised (1894), this fluid was made by dissolving 

 5 per cent, of mercuric bichloride and 5 per cent, of glacial acetic 

 acid in the required amount of Miiller's fluid (XI, A, p. 69). If 

 Miiller's fluid be had already made up, this will be the quickest 

 way of making Zenker's fluid. The sodium sulphate called for 

 in the formula for Miiller's fluid is now considered unnecessary 

 in Zenker's fluid, but it does no harm. In other respects it will 

 be seen that the mixture is the same. 



Zenker's fluid has excellent penetrating powers, and there- 

 fore may be used with larger objects than expedient with Van 

 Gehuchten 's fluid. It is also one of the very best fixing agents 

 for general histological purposes. 



Several days m the fluid does not usually injure the tissue, 

 but it is thought best to remove it after 12-24 hours. Wash in 

 water and then with an iodine solution to remove the crystals 

 (see 2 below), and then preserve in 70 per cent, or 80 per cent, 

 alcohol. 



C. Lavdowsky' s mixture (modified). — 

 Distilled water, 40 volumes. 

 95 per cent, alcohol (com.), 50 volumes. 



^j r — \ /» J~ • — • 



40 per cent, formaldehyde (com.), 10 volumes. 

 Acetic acid (glacial or cone), 2 volumes. 



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