92 FIXATION 



various cells by several authors, especially Strangew^ays and 

 Canti ^^^ and Policard, Bessis, and Bricka.*^^ The effects described 

 are those produced by the fixative itself, without subsequent 

 dehydration or other treatment. 



Methods of washing out. No comment is necessary here. 



Effects on dyeing. The effects of different fixatives on the affinity 

 of tissue-constituents for dyes have only been briefly touched on in 

 the preceding part of the book, because it is thought better to dis- 

 cuss this subject in the part dealing w^ith dyes (p. 202). The in- 

 formation is nevertheless summarized here, so that no one who 

 uses chapters 5 and 6 for reference will be inconvenienced by 

 the absence of any mention of this important aspect of fixation. 



Effects on the histological picture seen in parajfin sections. The 

 grading of fixatives, mentioned under this heading, has been fully 

 described on pp. 72 to 75. It is important to remember that this 

 system of grading is based on judgements made from the point of 

 view of routine histology. The fact that a fixative falls in one of the 

 lower grades by no means necessarily condemns it. It may have 

 virtues that are only brought out by mixture with other fixatives, 

 or it may be useful for some particular purpose in cytology or 

 histochemistry, or give good results when some other method of 

 embedding is used. 



The attempt is made under this heading to present a general 

 picture of what is seen in the finished preparation, by integrating 

 the results of the grading- test with the findings of Tellyesniczky,^^' 

 Zirkle,^^^' ^" Pischinger,*^^ and Casselman.^^^ These authors did 

 not all use the various fixatives at exactly the same concentra- 

 tions ; but despite this, and despite the diversity of the cells stud- 

 ied, it is possible to draw certain general conclusions. 



Compatibility with other fixatives . No comment is necessary here. 



ETHANOL (ethyl alcohol) 



Standard concentration for fixation. Absolute (100%). 



Formula and formula-weight. C2H5OH. 46-0. 



Description. Ethanol is a light fluid (specific gravity 0-791 at 

 20° C), miscible with water in all proportions. It boils at 78° C and 

 solidifies at about — 112° C. If free from water it gives no cloudi- 



