46 
allowed to reach 65° C, (109° F’.), as Van Bemmelen reports. When 
this temperature is kept up for some time or is allowed to rise some 
degrees higher, the tobacco loses its power of heating up again when 
the heap is repacked. The oxidase and catalase are now killed. 
Such tobacco is called “cooked.” It is knotty and curled and the 
fiber has lost much of its elasticity.” 
NOTES ON THE BACTERIAL HYPOTHESIS OF SWEATING. 
Although it was shown in Report No. 59 that Suchsland’s bacterial 
hypothesis of the sweating of the tobacco is unfounded -and that the 
true cause of the oxidation in the sweating process must be attributed 
to the presence of oxidizing enzyms in the tobacco leaf itself, never- 
theless some persons still adhere to the bacterial hypothesis. Butitis a 
simple matter for anyone to convince himself by direct microscopical 
examination of scrapings from moistened sweating wrapper leaves that 
the numerous bacteria which would be expected, by the hypothesis, 
are not there. Even if we assume that the supposed tobacco bacteria 
are characterized by extraordinary capacities of oxidation and fermen- 
tation, and that therefore a restricted number might account for a 
great deal of work, several millions at least should exist for every 
square inch. Further, it is evident that the conditions on the tobacco 
leaves are most unfavorable for bacterial growth. It was pointed out 
by the writer that the water content of a fermenting wrapper leaf is 
utterly insufficient to bring the nutritive compounds from the interior 
of the cells to the surface, the moisture being barely sufficient for the 
proper imbibition of membranes and cell contents. The easily soluble 
matters, such as oxidizing enzyms, will no doubt dissolve, but this solu- 
tion will be retained in the chief mass of the cell contents. 
Let us assume that all the water of a sweating leaf would be ayail- 
able for the cell contents—none being retained by imbibition of the cell 
membranes—and, further, that one-half of the cell contents is easily 
soluble in water, although in reality two-thirds are easily soluble in 
their own weight in water. A fermenting wrapper leaf with a water 
content of 20 per cent® would then contain a solution of organic matter 
of a strength of 50 per cent, since ripe wrapper leaves of good quality 
and capable of fermentation contain in the dry substance an average 
of 40 per cent of matter soluble in water.* In such a solution of 50 per 
cent of organic substances bacteria can not multiply. Even mold 
'Landw. Vers. Stat. vol. 37, p. 383. 
2 This is the experience of tobacco manufacturers of Florida, and has been men- 
tioned to the writer by Mr. M. L. Floyd. 
°'The tenacity and cohesion of wrapper leaves are generally seriously injured as 
soon as the water content is increased above 27 per cent while the sweating is 
going on. 
*Of course the percentage of soluble matters varies considerably in different 
grades of tobacco. 
