8o 



FIXATION 



practical difficulties in their use, especially in the flattening of 

 sections and their attachment to slides. 



'For the good working of many reagents it is of the greatest 

 importance that they should be dissolved in a medium that 

 cannot itself produce disorganization by osmotic disturbances. 



ETHANOL, ^^ 



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Zi 80 - 



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LU 



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a. 



If) 

 < 



o 



ALIVE 



IN 

 RINGER 



FIXATIVE 

 24 HR5. 



ETHANOL, 

 ABS. 



XYLENE 



CANADA 



BALSAM 



AFTER 



PARAFFIN 



FIG. II. Graph showing the effect of fixation and 

 subsequent treatment on the volume of the nuclei 

 of cartilage-cells (scapula of Salamatidra tnacu- 

 losa). Each point represents the mean of 20 

 measurements. 



(From the data of Hertwig.**") 



Therefore, for instance, for the preservation of marine algae 

 alcoholic solutions and solutions in distilled water are to be 

 absolutely rejected. Parallel experiments with picric acid, osmic 

 acid, and iodine dissolved in alcohol, in distilled water, and in 

 sea-water show without exception that only the solutions in 

 sea-water give really good results, when one uses delicate 

 objects.' 



These statements were published in 1882 by Berthold,^" who, as 

 we have seen (pp. 40 and 66), was one of the first to approach 

 the problems of fixation scientifically. We do not yet understand 



