The tobacco plant, NICOTIANA TOBACUM, belongs to the order Solanaceae, which also includes belladonna, capsicum, henbane, and likewise the common potato. Its active principle, an alkaloid--nicotine or nicotia --is combined with a vegetable acid. Some of the alkaloids, such as morphine, strychnine, &c., are crystalline in character, but this, along with a few others, is liquid. A single drop of it is fatal to the smaller animals, a cat or Even as it is, the first smoke usually produces characteristic results. There is generally pallor of the face, nausea, and vomiting. Usually a cold, clammy sweat breaks out, and the heart seems as if it were about to stop. The system, however, gradually becomes habituated to its action, and these symptoms do not reappear. Seeing that this somewhat unpleasant apprenticeship is uncomplainingly served, it is evident that in smoking there must be some powerful attraction. There are many, indeed, who persist in it when it is doing them an inconceivable amount of injury. It is a fortunate thing that almost all of the nicotine passes off, or is burnt up, or else the effect would be more markedly disastrous. But the pleasurable effects of tobacco are derived in great part from the volatile alkaloids formed during combustion. The alkaloids which develop during the smoking of a pipe are entirely different from those of a cigar. In a pipe, according to Vold and Eulenburg, the tobacco yields a very much larger proportion of volatile bases, especially of the very volatile and stupefying pyridine. On the other hand, a cigar produces but little pyridine, but more of the less active collidine. It is well known that very much stronger tobacco can be smoked as a cigar than as a pipe. As a matter of fact a cigar which could be enjoyed as a cigar, would cause sickness if cut up into small pieces and smoked in a pipe. This pyridine to which reference has just been made has lately been brought forward as a remedy for asthma. Now, the effect of tobacco in cutting short an attack of this latter malady is, at times, very marked. And Professor See, the eminent French physician, believes that the pyridine is the relieving agent. In the earlier part of this section I have attempted to form a provisional classification of people as far as the effect of tobacco is concerned. Firstly, those upon whom tobacco in any shape or form is an absolute poison; secondly, those who can enjoy a very small amount-daily; and thirdly, those who are able to smoke in moderation. Now, while those who use tobacco with wise discretion appear to be none the worse for it, yet it unfortunately happens that far too frequently there is no limit to this discretion. It is too often the case, therefore, that quite a serious amount of damage to health results from excessive smoking. It requires a good deal of judgment, and even more resolution, to use and not abuse tobacco.