34 FIXATION 



concentration as in the living cell, and both globular and fibrous 

 ones are present. 



Gelatine/albumin gels are stabilized against warmth by fixatives 

 that will not stabilize gelatine alone. If gels that have stood in 

 fixatives for i8 hours be rinsed and transferred to a large volume 

 of water at 37° C, two hours later they will present the appearances 

 recorded in table i. 



TABLE I 



The appearances shozvn by gelatine j albumin gels soaked in various fixatives 

 for 18 hours and then left for 2 hours in zvater at 37° C^^ 



The appearances will be the same after four days. (The gel fixed 

 with osmium tetroxide was not observed beyond one day.) 



Certain facts stand out from the experiments with gelatine and 

 gelatine/albumin gels. The most obvious relate to the non-coagu- 

 lant fixatives. It is clear that two of these (acetic acid and potas- 

 sium dichromate) do not fix these two proteins, in the circum- 

 stances of the experiment; the other two (formaldehyde and 

 osmium tetroxide) give much the best fixation of all the substances 

 tried. The strong mineral acids, though coagulant fixatives, give 

 very feeble stabilization of form. The other coagulant fixatives 

 roughly stabilize the form of the gel. 



The reactions of most fixatives with nucleoproteins are very 

 different from those with albumin. For the pioneer work on this 

 subject, see Berg.^^' ^^ Convenient experiments of the same nature 

 are described in the Appendix (p. 317). The results of such experi- 

 ments are recorded in table 2. 



