CHAPTER VIII 
THE VENETIAN TURPENTINE METHOD 
Just as glycerin jelly is superior to glycerin as a mounting medium, 
so Venetian turpentine is superior to glycerin jelly. While the method 
was described by Pfeiffer and Wellheim 1 thirty years ago, it received 
no recognition in the United States or even in Europe. I made a 
casual trial of the method when preparing the first edition of this 
book, but the preparations were such miserable failures that the 
process did not seem worth mentioning. The method was next 
brought to my attention during a demonstration in Strasburger’s 
laboratory at Bonn. He was using preparations of Zygnema and 
Spirogyra, the staining of which surpassed anything I had ever seen. 
He remarked that it was not worth while to consult the lengthy 
article, because his preparations had been made by the authors and 
no one else had made a success of the method. However, when I 
returned, I made a careful study of the process, and finally learned 
to use it successfully. The details as given in this paper were too 
indefinite for practical use, but, after one has learned the method 
the article can be read with profit. 
The great practical advantages of the method are that prepara¬ 
tions are as hard and durable as balsam mounts, and that a much 
greater variety of staining is possible than in case of glycerin mounts. 
The principal features of the method are that material is brought 
from pure glycerin into alcohol, and from alcohol into Venetian 
turpentine, without passing through xylol or other clearing agent. 
After fixing and washing in water and staining in an aqueous 
stain, e.g., iron-alum haematoxylin, the process is as follows: 
1. 10 per cent glycerin until concentrated. 
2. Wash the glycerin out thoroughly in 95 per cent alcohol. 
3. Complete the dehydration in 100 per cent alcohol. 
4. 10 per cent Venetian turpentine in an exsiccator until the turpentine 
becomes thick enough for mounting. 
5. Mount in the Venetian turpentine. 
1 Ferdinand Pfeiffer and R.v. Wellheim, “Zur Preparation der Susswasseralgen,” Jahrbiichern 
fiir wissenschaftliche Botanik, 26 : 674-732, 1894. 
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