100 



(8; Fuiv xylol (2 changes two ininutos each. 



ir Ihc clol is very thick il is necessary lo cieliydrale 



longer in xylol-acelone. 



The methylene blue solution is prepai'ed in the following 

 manner: Saturated alcoholic solution of methylene blue 

 30 c. c. 



KOH ^1—10,000) 100 c. c. 



The nu^thylene blue is allowed to ripen in the incubator 

 for a month. 



The azur-blue solution is prepared as follows: 

 Azur II — 0,3 gram 

 Alcohol (95 o/o) lOc.c. 



The two staining methods just described are very sa- 

 tisfactory for the standard work and especially the me- 

 thylene blue method gives very good pictures for micropho- 

 tographic work. 



If one has to investigate the intimate structure of the 

 cultivated tissue, sections can be made, and this is a very 

 valuable method for studying the relations of the cells 

 to the entire clot. 



Sections of the cultures are made in the usual way. 

 The cultures are fixed on the cover slip and they can then 

 be removed carefully with a scalpel and passed through 

 the different dehydrating solutions and finally be embedded 

 in paraffin. C.oUodion can, of course, also be used and 

 is often easier to use for such small delicate subjects as 

 are the tissue cultures. 



C o h n h e i m's idea of using gold impregnation method 

 on the corneal cells, in order to get the characteristic 

 outlines, suggested that this method perhaps could be ap- 

 plied in (staining) the cells in tissue cultures. I tried the 

 gold method of L 6 w i t's in the following wa}'. In a dark 

 room the coverslip bearing the plasma clot and tissue culture 

 was put into concentrated formic acid for 2 — 3 minutes and 



