576 



NATURE 



[October i i, 1900 



Perseids, with the usual result of latter-day meteor watch- 

 ing — we saw none. However, it was a novel and 

 exceedingly pleasant experience to be there lying under 

 the stars, the greatest telescope on earth immediately to 

 one's side, the highest buildmg in the world towering 

 over our heads. 



It is to be hoped that after the Exhibition is over 

 the telescope will find a resting-place under the Home 

 Government at some station out of the city, where the 

 purity of the atmosphere will allow of its power being 

 efficiently used. C. P. Butlp:r. 



TOBACCO. 

 'IXT'HEN Columbus landed in 1492 in the West Indies 

 * * he found the natives smoking a herb wrapped in a 

 maize leaf, and the name of the herb was Tobago. In 

 1560 Jean Nicot distributed plants raised from seed to 

 various parts of Europe. These two events give us the 

 clue to the popular and scientific names of a drug the 

 •cultivation and preparation of which have now attained 

 such enormous importance that Governments are sup- 

 ported by the revenue derived from its taxation, and 

 •colossal fortunes are made by its sale. Some idea of the 

 scale on which the industry is carried on may be 

 gathered from the statistics recently published in the 

 " Year-book of the United States Department of Agri- 

 culture for 1899," where we read that during that year 

 266,661,752 pounds of tobacco, 4,542,016,570 cigars and 

 4,590,388,430 cigarettes were prepared in the United 

 States alone, yielding a revenue to the Government of 

 52,o43,859"o5 dollars. 



Small wonder then that the cultivators of so valuable 

 <i plant have shown great interest in all the processes of 

 raising, planting, manuring and gathering the crop, and 

 of drying, curing and preparing it for market ; or that 

 consternation has arisen in their midst at the origin and 

 spread of a disease which attacks the golden leaf, and 

 bids fair to ruin the crop in some districts. It happens, 

 moreover, that biological problems of wide significance 

 a.re arising in connection with the complex art of fer- 

 menting the leaf so as to obtain the best flavour and 

 strength, as well as in regard to the " Mosaic disease " 

 above referred to, and the experience of Dutch growers, 

 of which an excellent account is now to hand in Koning's 

 " Der Tabak, Studien ueber seine Kultur und Biologie " 

 (Amsterdam and Leipzig : W. Engelmann, 1900), shows 

 that the employment of scientifically trained botanists in 

 the technical laboratories of tobacco plantations is likely 

 to be as usual an event in the future as in breweries 

 and bacteriological laboratories. 



The tobacco plant is exceedingly small in the seedling 

 stage— eighteen thimblefuls of seed suffice for a hectare, 

 i.e. two and a half acres of land — and is very carefully 

 raised in pots and manured with pigeon's dung, planted 

 out and weeded with extraordinary precautions against 

 numerous enemies, and the leaves eventually picked by 

 hand, sorted, tied into bundles and hung to dry. It is 

 a very exhausting crop, and requires much potash ; and 

 an astonishing amount of information has accumulated 

 concerning the effects of different soils, manures, climate 

 and other factors of the environment on the properties 

 of the leaves. Moreover, there are numerous cultivated 

 races in existence in the various tobacco-growing countries, 

 as always occurs with planted crops. 



During the process of slow drying the leaf may remain 

 ■alive for two to three weeks, and the contained starch 

 is converted into sugar, and further alterations result in 

 an increase of acids. Proteids diminish and amines 

 increase, but the nitrates and alkaloids (nicotin) should 

 4andergo no change. The slow alterations referred to 

 are essential, and due to enzyme and other actions in 

 •the still living leaf ; in artificially or rapidly dried leaves 



NO. 1615, VOL. 62] 



the arrest of such changes materially affect the flavour 

 and burning of the tobacco, and naturally much turns 

 on the age and quality of the leaf itself, the soil and 

 season and other conditions of growth, &c. 



The dried or " cured " leaves are next submitted to 

 fermentation, a process of vital importance in the opinion 

 of the tobacco expert, since it is this which determines 

 the finer flavours and odours of the manufactured pro- 

 duct. Fermentation is started by damping heaps of 

 15,000 to 30,000 lbs. of the dried leaves, packed in a 

 special manner, and carefully watched by experienced 

 workmen as the temperature rises. The process occu- 

 pies three to four months, and the leaves are turned 

 about once a month. The temperature rises to about 

 50-56" C, and a loss of vapour, accompanied by a sweet 

 and sharp odour, is noticed. The reaction may be 

 neutral, though in some cases ammonia is given off, due 

 to the action of undesired bacteria. 



As would be expected, the fermentation is always 

 accompanied by bacteria ; but it has long been in dis- 

 pute whether the essentials of the process are due to 

 bacteria or to the action of special enzymes in the cells 

 of the leaves. 



Suchsland's researches had convinced him, not only 

 that the fermentation is due to bacteria, but that a peculiar 

 species of bacteria was specially concerned in the pro- 

 duction of the approved flavour, and that the desirable 

 properties of Cuban tobaccos could be imparted to 

 inferior growths by introducing this species into the fer- 

 mentation. Loew, on the other hand, maintained that 

 the aroma and flavour depend simply on the action of 

 enzymes or other cell-contents in the leaf itself 



Koning has investigated the various bacteria found in 

 the fermenting heaps, and followed the changes induced 

 in the tobacco. 



Put generally, the fermented tobacco undergoes little 

 or no change as regards the total nitrogen or the nicotin, 

 but organic acids diminish, and the sugars and nitrates 

 are destroyed, and various aromatic substances are 

 formed which affect the quality of the product. 



Among the bacteria isolated Koning claims to have 

 found the species concerned in this remarkable neutral 

 fermentation, and which imparts the aroma and flavour 

 desired, and thus confirms Suchsland's results. He states 

 that tobacco infected with the specific bacteria, fer- 

 mented and made up, and then handed to experts, was 

 selected by the latter as the superior from specimens 

 containing other kinds. There is more than a touch of 

 the dramatic in this scene of the experts sitting down to 

 smoke a pair of cigars each, in packets of two, and labelled 

 a and ^, c and </, &c., only ; but the evidence appears 

 conclusive. 



During the last ten years increased attention has been 

 drawn to a disease of tobacco leaves, which causes 

 irregularly alternating light and dark patches, and is 

 known as the " Mosaic disease." Koning has established 

 that this is infectious, and is carried through the fields 

 by the fingers of the workmen who "top" the growing 

 plants by pinching off the buds. He has examined the 

 various fungi known to cause leaf-diseases in tobacco, 

 and cannot refer it to these, and the presumption that it 

 is a bacterial disease was strengthened by finding that 

 certain manured soils were almost sure to have badly 

 diseased plants on them ; and that experiments showed 

 that if a bit of diseased leaf, or a little of the sap from 

 such is rubbed into a wound, the young leaves formed 

 above the wound contract the disease. The same result 

 follows if such sap is placed at the roots of healthy 

 plants. But infection fails in all these cases if the sap 

 is previously boiled. 



Here may be mentioned that Adolf Mayer had proved 

 the infectious nature of the filtered sap in 1885, and 

 Beijerinck, working at this disease a short time ago 

 (1898), had come to the conclusion that since no 



