THE MICROSCOPE 



APRIIv, 1896. 



Number 4o New Series. 



Formalin as a Hardening Agent for Nerve Tissues. 



WILLIAM C. KRAUSS, M. IX, 



BIFFAI.O, N. Y. 



[Member of the American Microscopical Society.] 



Formol, Formalin, or Formaldehyde was discovered by 

 A. W. Hoffman in 1863 while passing wood spirit and air 

 over a red-hot platinum spiral. If the vapor is brought 

 into water to its point of saturation, a forty per cent solu- 

 tion of formaldehyde is obtained, which has long been 

 known under the name of formol. That Formalin pos- 

 sessed antiseptic as well as hardening powers we owe to 

 the investigations of Dr. F. Blum, and these facts induced 

 tlie elder Blum to make an extended series of investiga- 

 tions in the hardening of animal and vegetable tissues in 

 the Senckenbergischen Institute at Frankfort, Germany. 

 His preliminary report was published in the Zoologischer 

 Anzeiger, 1893, No. 434, and a more detailed report in 

 the Berichte iiber die Senckenbergische Naturforscher 

 Gresellschaft, 1894, p. 195. Here he details his experience, 

 which in brief is as follows : Several human embryos 

 were finely preserved in formol diluted with ten to 

 twenty parts of water. Small embyos with amnion in- 

 tact were preserved and the amniotic fluid remained trans- 

 parent, so that the structural parts of the foetus and the 

 umbilical cord were recognizable. The mouse, hamster, 

 and porpoise, were nicely preserved, the hair firmly in 



