tially responsible for it. He used samples sterilized, and others unsterilized, taken from the same lot of tobacco; some was kept at a uniform temperature and some simply prevented from cooling below a certain point. He concludes that at a temperature below 104° F., or above 158° F., and possibly varying little from 122° F., the action is a purely chemical one, with which lower organisms have nothing to do. Theoretically, he believes the changes brought about by snuff fermentations might be accomplished entirely without the aid of lower organisms. In practice, however, they serve to start the changes and develop the heat that is necessary to setting up the more rapid oxidations. "The physical properties of a good snuff tobacco," he says, "can be secured in two months at 158° F., in less time at 176° F., and in ten to twelve days at 212° F., while the desired internal chemical changes are accomplished in the same. period at the latter temperature." He finds that a new fermentation is set up every time the tobacco is turned and repacked, and that the sum of the carbonic acid and oxygen in the air of the cases always exceeds 21 per cent, and may run up to 35 per cent. This is regarded as an evidence of the activity of anaerobic ferments. Schloesing found present a bacillus and a diplococcus. He compared the snuff fermentation with the aerobic fermentation of stable manure. Fesca and Imai think it more closely comparable to the process of ensilage. But Behrens claims that, owing to the watery condition of silage, the fermentation of brown hay, a dryer product not in use in America, is more strictly analogous.

*

In the "sweating" of ordinary leaf, especially as practiced in Germany, Nessler says that a temperature of 106° F. is attained in the heap at a depth of one foot

Landwirthschaftliches Jahrbuch, 1888, p. 327.

in course of half a week and, at three feet, a temperature of 129° F. It is needful to cover the heap with cloths to absorb the condensing moisture, which would otherwise condense in the upper layers of tobacco, and cause rotting and molding. Smoking tobacco is not to be allowed to heat above 122° F. Behrens believes that these changes are to be ascribed chiefly to the action of anaerobic ferments, although a local action of aerobic forms at the same time is not excluded. He found in sweated tobacco vigorous individuals of the widely distributed aerobic form, Bacillus subtilis, and also an aerobic Clostridium, which, like Clostridium butyricum, formed endospores. He does not think the latter especially active, but recalls the fact that Cohn attributes the fermentation or spontaneous heating of damp hay and stable manure to the former organism. Behrens* also etates that he has found the mold, Aspergillus fumiqatus in sweating tobacco, upon six out of eight samples from three different dealers. While this organism is regarded by Cohn as the cause of the heating of piledup malt, it is not supposed to play any large part in the sweat.

Behrens endeavored to ascertain the changes which occur during sweating. He found a loss of 'only 2.5 to 5.6 per cent of dry matter, although others put it as high as eight 'to twelve per cent-in the latter case, the loss of water is included. This loss falls chiefly upon the soluble carbohydrates and less upon the non-volatile organic acids. There is no loss of nitrogen, yet onethird of the nicotine disappears; it possibly serves as food for the lower organisms, as an earlier research t has shown that Botrytis cinerea can eat it. There is a loss of nitrate nitrogen and a diminution of the other

⚫ Centralblatt fur Bakteriologie und Parasitenkunde, 11 (1894) p. 335 seg. ↑ Zeitschr. f. Pflanzenkrankheiten, 3 (1893), pp. 85-86,

soluble substances. Butyric acid is present as one of the products of the sweat.

The investigations of Cohn and others have shown that the flavors of butter are largely due to the products formed by special ferments active in ripening the cream. Pure cultures of one ferment produced nauseous butter; of another, a butter with all the delightful aroma and flavor of the finest grass butter. Selected cultures of the latter bacterium are now on sale to the dairymen of America.

SPECIAL CULTURES FOR SPECIAL FLAVORS IN THE LEAF.

It has recently been queried whether tobacco, which was known not to attain its finest flavor and aromatic smoking qualities until after the sweat, might not, in the finer varieties, such as the better Cuban brands, as contrasted with less excellent kinds, owe its excellence in the former cases to the favoring influence of some special bacterial ferments.

It has long been a matter of comment among the more expert buyers and manufacturers, that cases, in the center of which "black rot" had developed sufficiently to injure the leaves immediately surrounding, yielded tobacco of a finer flavor, more nearly approaching the Cuban, than was obtained from other cases of the same lot that escaped the black rot.

Emil Suchsland,* several years since, published a most suggestive paper upon this subject, from which I largely quote: "In connection with bacteriological investigations as to the influence of certain physical conditions upon bacterial development, made by me under the direction of Professor Zöpf, I have, for a long time, been studying the nature of the tobacco-sweating process. This process is, it is well known, of the high

79-81.

Berichte der deutschen botanischen Gesellschaft, 9 (1891), pp.

est influence upon the usefulness and excellence of all varieties of tobacco. Thus far it has been regarded as a purely chemical process; but it has always seemed to me more probably a fermentation similar to the lactic, butyric and acetic acid fermentations, which are caused by bacteria. In all sweated tobacco thus far examined, it is worthy of note that bacteria are present in large numbers, bnt in small variety. At most, only two or three species occur, belonging especially to the Bacteria proper, though sometimes to the Micrococci. Tobacco of the following sorts was tested: Havana, St. Domingo, Kentucky, Brazil, Turkish, Grecian, Russian, Pfalz, Alsace-Lorraine, Breisgau and Uckermark. Pure cultures of the bacteria upon these sorts were prepared. When tobacco of another sort than that from which the bacteria were taken, was inoculated by the pure culture of the latter, the tobacco thus inoculated took on the flavor and odor of the tobacco from which the bacteria were derived.

"In view of these facts, the sweating process assumes more importance than it has thus far held. Heretofore, the aim in Germany has been to improve the tobacco by better culture and by the introduction of improved varieties; the latter soon deteriorate, however, in this climate, especially since the right kind of ferments are not present in the sweat. Our tobacco always suffers a sort of wild fermentation. But it is now possible to introduce the better ferments into our own tobacco during the sweat. Every experiment I have made has given positive results. So surprising have been the changes in Pfalz tobacco, that excellent judges of domestic sorts have declared the tobacco thus sweated to be a foreign product.

Unfortunately, Suchsland has never carried further the work thus interestingly outlined. Nevertheless, a firm in Berlin, Hermann Giesecke, offers for sale pure

cultures of the bacteria active in the sweating of the better tobacco, and Behrens, who has most recently looked into the subject, by way of investigation, is, though rightly conservative, strongly inclined to accept the practicability of Suchsland's suggestion.

Clearly, the matter is one of vital importance to American growers and manufacturers. It is worthy of the simple, preliminary experiments that packers and makers can carry out, as well as of the more perfectly controlled investigations of our tobacco experiment stations. If, by proper inoculations and maintenance of established conditions of moistening with water, or other more suitable liquid, and of temperature, we can impart to local tobacco the flavor and aromatic smoke of Cuban and other tropical tobaccos, it will be possible to dispense with a large part of the present importations for fillers.