IOWA ACADEMY OP SCIENCES. 
147 
THE USES OF FORMALDEHYDE IN ANIMAL MOR- 
PHOLOGY. 
BY GILBERT L. HOUSER. 
By the term formaldehyde^ I wish to designate a 40 per cent 
solution of the gas formaldehyde in water. Several articles 
answering to this description have been placed on the market 
under trade names such as the “Formalin” of Sobering, the 
“Formol” of Merck, and the “Formalose”of Richards & Co. 
So far as I have tested these various preparations, they all 
agree as to composition, and yield perfectly similar results. 
My attention was first directed to formaldehyde as a morpho- 
logical reagent in July, 1894, and I have been using it in my 
work, and have experimented with it in various directions since 
that time. It certainly possesses several most remarkable 
properties; so remarkable, in fact, that certain phases of lab- 
oratory work in animal morphology are ultimately destined to 
undergo a revolution through its use. 
I. FORMALDEHYDE AS A GENERAL PRESERVATIVE. 
It has been urged many times that the zoological specimens 
placed in the hands of students for class-work are too often 
mere caricatures of the living animals themselves, and that 
various erroneous conceptions about nature are thus sure to 
arise. Granting that we should, as far as possible, use fresh 
material for study, the fact remains that there are many animals 
which must be preserved if we are to study them at all. The 
whole of the group Echinoderma, and, with one exception, all 
the members of the Coelentera, are cases in point. Such ani- 
mals have to be preserved at some distant point and transported 
to us. Now, formaldehyde has its most important and its most 
far reaching application in this particular field of morphological 
work. It is the best general preservative of material for class- 
work that has yet been discovered. The peculiar qualities 
which confer upon it this distinction are as follows : 
