1897.] Microscopy. 95 
capsule, and recti muscles were much better preserved when alcohol 
was used. 
The chief objections to formal are: 
1. It does not preserve well the plexuses and membranous parietes 
of the brain. 
2. It is in unstable chemical equilibrium. 
3. The conditions attending its use are favorable to chemical change, 
t. e., (a) solution, (b) moderate heat, (c) the presence of substances 
themselves in unstable chemical equilibrium. 
4. The large excess of water present causes tissue to swell and aids in 
dissolving connective tissue. 
5. The cost of a given solution is less than that of alcohol, but the 
renewal of solutions brings the total expense up to nearly that of 
alcohol free of tax; and in the writer's judgment, excepting for brains 
and perhaps for aquatic vertebrates, the final result is less satisfactory. 
SuMMARY. 
1. The most suitable contraction of the name Formaldehyde is Formal. 
Formalin is meaningless. Formol is incorrect. Formalose is mislead- 
ing. 
2. Some uniform standard for preparing solutions is desirable. 
3. Formal is an unstable chemical compound. It polymerizes on 
standing. A precipitate of Para- and Metaformaldehyde, insoluble in 
water at ordinary temperatures, is formed and the solution is weakened 
by the amount of the precipitate. 
4. Para- or Metaformal may be procured in the dry form and solu- 
tions can be prepared when desired by simply dissolving the required 
amount in hot water (70° C.). This would be the more economical 
way to nse formal. 
5. Formal coagulates proteids and dissolves connective tissue. The 
action proceeds slowly and the final effect is reached in about yow 
months. 
6. Solutions of formal will freeze so that it is unsafe for the — 
of museum preparations. 
T. Formal, as a general preservative for terrestrial vertebrates, is 
ihadlicfukonh 
Formal appears to give good results for: 
a. The fixation and preservation of bfhins for the study of gross 
morphology and fissures. 
b. For the preservation of the cornea aol vitreum of the eye. 
c. For the Golgi method of staining nerve cells. - 
