when fed on animal blood, and which produce the various diseases known as blood-poisoning of various kinds. There is the seed whose growth causes cholera, and another whose growth causes scarlet fever, and another whose presence means typhoid, and another which results in splenic fever, and another which generates small-pox, and probably many more besides, which grow at the expense of animal life or health, — of some of which Professor Tyndall has given a graphic account in the paper on fermentation in the November Fortnightly. Unquestionably, either the minute organic world is beginning to avail itself of the great advantages which its all but invisibility gives it in competing with men, or if it is only doing now what it has always done, but what is only just beginning to be understood; a greater importance is now attached to its proceedings, partly because the danger is understood, and partly, — perhaps even more, — because the weaker constitution of modern man is now so much protected against these dangers that the race suffers more, though the individuals suffer less. Of course it is obvious that, when fewer effective causes are at work to thin out the stock, those which injure it, without diminishing its fertility, tend to render it more sensitive to all external influences for the future, and therefore make the very disease against the power of which the new remedies or alleviations have been found, more menacing in some respects to the health of the race, though less so to the individuals who suffer from it, than it was at a time when it was more generally fatal. It may well be that the very knowledge which science has gained of the new dangers to which man is subject, has rendered these diseases of greater physical consequence by diminishing their fatality. The more delicate, better-guarded, longer-lived, but more sensitive constitutions which science has taught us how to protect to an average age beyond that to which even the healthy lived in former times, are necessarily more overshadowed by the physical ills of which we know so much more than our ancestors ever were, — not only because of our new knowledge, but because the tenderer inherited constitution, which has been piloted through so many dangers, is more keenly alive to such dangers than were the more hardy constitutions which had survived in spite of running the gauntlet of much more fatal ills. Modern man, whose food and drink are beset by Colorado beetles and phylloxera, whose clothing is threatened by pibrine, and whose life itself is haunted by all sorts of minute spores which so feed on his blood as to generate fever, cholera, and a great variety of plagues, is obviously in one respect not the better, but the worse for the knowledge which teaches him how to evade the worst consequences of these plagues. He has less to fear from them individually, but they have more part in him than they had when they produced more deadly results. They have inoculated him, and though they count fewer victims slain, they transmit into a remoter future the weakness and suffering which they cause. The race of men whom the common germ-poisons no longer kill off retains more of the stamp of their paralyzing effects than the race of men which succumbed at once to the first onset of the unknown foe.
This is why we cannot altogether share the enthusiasm, and can by no means adopt the sentiment, of that somewhat declamatory peroration to Professor Tyndall's Glasgow audience which ends the lecture published in the last Fortnightly. "This preventible destruction," says Professor Tyndall, referring to the havoc caused by germs of disease floating about the air, "is going on to-day, and it has been permitted to go on for ages, without a whisper of information regarding its cause being vouchsafed to the suffering, sentient world. We have been scourged by invisible thongs, attacked from impenetrable ambuscades, and it is only to-day that the light of science is being let in upon the murderous dominions of our foes. Men of Glasgow, facts like these excite in me the thought that the rule and governance of this universe are different from what we in our youth supposed them to be, — that the inscrutable Power, at once terrible and beneficent, in whom we live and move and have our being and our end, is to be propitiated by means different from those usually resorted to. The first requisite towards such propitiation is knowledge; the second is action, shaped and illuminated by that knowledge. Of knowledge we already see the dawn, which will open out by-and-by to perfect day; while the action which is to follow, has its unfailing source and stimulus in the moral and emotional nature of man, — in his desire for present well-being, in his sense of duty, in his compassionate sympathy with the sufferings of his fellow-men." And the drift of all this rather excited eloquence was not merely what is here implied; the true clue is given by a previous passage, in which it is intimated that man ought to seek this all-potent knowledge at the ex-
