464 The American Naturalist. [May, 
MICROSCOPY. 
The Proper Angle for the Razor in Paraffin Sectioning.— 
In a discussion between Dr. M. Heidenhain and Dr. B. Rawitz relative 
to section cutting and the staining of microscopic preparations, the 
latter person’ upholds the advice that he gave in his “ Leitfaden,” and 
adduces experimental proof to show that the microtome knife should 
be placed at an acute angle to the stroke rather than at a right angle. 
When placed at the latter angle the sections according to their thick- 
ness, are always more or less crowded together, thus distorting the finer 
structures of the tissue cut. The @xperimeatal proof consists of the 
measurement of sections cut with the knife at a right angle, and with it 
at an angle of 45°. The sections were from a block of paraffin measuring 
203 x 113 mm., and had a thickness of 15, 10» and 5y. With the knife 
at the acute angle they all measured 11 mm. in breadth, while with the 
knife at a right angle they measured 94 mm. for the 15x, 9 mm. for the 
10⁄4, and 8 mm. for the 5y sections, thus showing a shrinkage of 2, 22, 
and 33 mm. respectively. In the case of the thinnest sections there is 
a loss in breadth of almost a third of the surface of the block, and 
such are somewhat incorrectly denominated ‘sections’. They might be 
called “ Quetschen.”—F. ©. KENYON. 
Formol, not Formal.—The paper by Bert B. Stroud in the 
January number of this Journal, induces me to make a few remarks 
regarding the nomenclature of the method of hardening by formol in- 
troduced by me into histological technique. Though I agree with the 
author that the terms formalin.and formalose are bad and meaningless, 
I cannot agree to the objection to the denomination of the original 
fluid as “ formol.” To call the solution by the name of formaldehyde 
is not to be recommended, as formaldehyde, C,HO, isa gas. The term 
formol is opposed by Stroud because the terminal syllable “ol” sug- 
gests an alcohol; but formaldehyde dissolved in water is no longer to 
be regarded as an aldehyde, but as a double alcohol, methylenglycol. 
z >C—O=Formaldehyd. | 
OH,0+-8,0=F noT Meth ylengl yen. 
1 Bemerkungen über Mikrotomschneiden und über das Färben mikroskopischer 
Präparate. Anat. Anz. XIII, 65-80. Separat from the author. 
