74 A RESUME OF THE USES OF FORMALIN. 



it is possible to make a report in fifteen minutes. Method II. 

 is used mostly for the examination of uterine curettings. The 

 author's practice is to have bottles containing a ten per cent, 

 solution of formalin in the operating room. The curettings are 

 immediately placed in one of these, and by the time they reach 

 the pathologist they are hard enough to make frozen sections of. 



Bender has also used formalin for making frozen sections, not 

 for preliminary hardening, as in Cullen's method, but for complet- 

 ing the hardening of specimens that have already been in alcohol. 

 He places pieces of tissues, two millimetres thick, that have been 

 in alcohol, in a one per cent, solution of formalin, and keeps them 

 there until the alcohol is completely removed. This requires from 

 half an hour to an hour. He then washes them well in water and 

 makes frozen sections. The tissue, he states, is rendered soap-like 

 in consistence by the action of the formalin. 



Ohlmacher states that formalin, when used in from two to four 

 per cent, solutions, acts as a powerful mordant for aniline dyes. 

 Cover-glass preparations are treated for one minute with the solu- 

 tion, washed well in water, and then stained in the cold. Or it 

 may be used instead of aniline oil or carbolic acid as a menstruum 

 for dissolving the dyes. One gramme of fuchsine or other aniline 

 dye is dissolved in ten cubic centimetres of alcohol, and this is 

 added to one hundred cubic centimetres of a four per cent, solu- 

 tion of formalin. Formalin methylene blue, made by dissolving 

 one gramme of methylene blue in one hundred cubic centimetres 

 of a four per cent, solution of formalin, makes an effective stain. 

 A saturated solution of safranin in a four per cent, solution of 

 formaUn gives a beautiful double stain when used after the formalin 

 methylene blue. Nuclei stain blue, plasma stains reddish. 



S. H. Gage has used the following solution as a dissociating 

 agent with good results : 



Normal salt solution ... ... i,ooo c.c. 



Formalin (forty per cent.) ... ... 2 ,, 



Formalin has been used by Hauser for preserving plate and 

 tube cultures of bacteria. His method is as follows: Plate cultures 

 in Peri's dishes have a piece of filter paper placed under the cover, 

 which has been moistened with ten to fifteen drops of formalin. 



