Another step that went along with the work on fermentation in general was the discovery of the causes of diseases in French grapes.
Bechamp, hearing of the commotion over this trouble in the vineyards, quietly took up a study of it in 1862, the year before Pasteur turned his attention to the subject.
- Bechamp exposed to contact with air:grape-must as found on the vines,
- grape-must filtered, and
- grape-must decolorized by animal charcoal.
They all fermented, but not equally so, and the moulds or ferments developed were not identical in these three experiments, which of course caused him to seek a reason for this.
On further experiments, with the rigid exclusion of all air (the whole healthy grapes, with stalks attached, being introduced directly from the vine into boiled sweetened water, cooled with carbonic acid gas bubbling through it), fermentation took place, and was completed in this medium, proving that air was not required. Hence the ferment must have been carried on the grapes, and was not airborne.
Professor Bechamp concluded that the organism causing the must to ferment must be carried on the grape, its leaves, or the vines, and that it might also be an organism injurious to the plants.
He published a volume on vinous fermentation in 1863, entitled Lecons sur la Fermentation Vineuse et sur la Fabrication du Vin, in which he gave an intelligent discussion of the subject.
He also presented two papers on the making of wine to the Academy, entitled Sur les Acids du Vin and Sur l’utilite et les Inconvienient du Cuvages Prolonges dans la Fabrication du Vin – Sur la Fermentation Alcoolique dans cette Fabrication.
In October 1864 he presented a communication to the Academy of Science on The Origin of Vinous Fermentation, an exhaustive account of the experiments described above.
This paper was a complete study of the subject, in which he proved that vinous fermentation was due to organisms found on the skins of grapes and also often found on the leaves and other parts of the vine. Hence at times, diseased vines might affect the quality of the fermentation and the resulting wine.
Thus by October 1864, Bechamp had several authoritative papers in print, but where was his super-learned rival?
In 1862 Pasteur was admitted to the French Academy through the influence of Biot and the Mineralogical Section, which based its nomination and support on Pasteur’s past work on crystallography; yet many attacks were made on his treatment of that subject, and he took the advice of friends to drop this line of work!
In March 1863, he met the Emperor and was soon sent to the vineyards to study the grape disease, with the prestige of having the Emperor’s backing.
He published several papers on the vines and their troubles in the latter part of 1863 and in 1864, but apparently was still riding his spontaneous generation theory which Bechamp had so completely exploded in 1858, and he did not guess correctly as to the cause of the trouble with the vines.
In 1865 he offered five papers, and others came later, but he does not seem to have hit on the right answer to the problem until 1872, when he made the great discovery that Bechamp was right again! In this year, Pasteur presented a memoir entitled New Experiments to Demonstrate that the Yeast Germ that Makes Wine comes from the Exterior of Grapes.
As Bechamp had made the same statement in his 1864 paper and it had not been disproven in the intervening eight years, it was a pretty safe bet for Pasteur to make!