The phthisical are attractive in personal appearance on account of their rich skin and hair colouring and their frequent brightness and vivacity, and their obvious delicacy also elicits a feeling of pity and wish to protect them. In consequence of this they easily marry, and they are as a rule very fertile. Galton[16] says: “There is fair doubt whether a group of young persons destined to die of consumption contribute considerably less to the future population than an equally large group who are destined to die of other diseases.” Now this phthisical type is very common with us indeed, and it appears to be an innate variation to which our race is liable. It is evident, therefore, that those people with the tuberculous variation who, even under the present circumstances, manage to contribute their quota to the population, would, were the bacillus tuberculosus altogether exterminated, contribute more than their share, and the type would become more common. And let it be remembered that this type, apart from the action of the bacillus, is a delicate and fragile one and liable to other affections, and the effect of giving the type any advantage in the struggle for life would surely imperil the well-being of the future of the race. When, some years ago, it was thought that a cure for phthisis had at last been obtained, great tribute was naturally and rightly paid to its discoverer; but had this cure proved as efficient as the more sanguine were led to expect, it would be terrible to contemplate the eventual suffering that would have resulted from the constantly increasing numbers of the phthisical type that would have been born with each generation. _If we stamp out Infectious Diseases we perpetuate Poor Types._ It is a hard saying, but none the less a true one, that the bacillus tuberculosus is a friend of the race, for it attacks no healthy man or woman, but only the feeble. It is like the bacillus of leprosy in this respect, but in this respect only, for leprosy attacks anyone living under certain unhygienic conditions. Remove these conditions--as we have done long ago--and the bacillus of leprosy disappears; its duties are over, like those of the extinct plants and fishes in the rocks. The tubercle bacillus on the other hand attacks a type to be found not only in the poor, ill-fed, and ill-conditioned, but also those who live well. It is a disease of all classes, and those who live in well-ventilated rooms, and who conform to every sanitary regulation, may still belong to the type who fall a prey to it. It is certain, therefore, that, improve the external conditions of life how you will, this type will remain. It is also as certain that in giving the type a better chance than it has already, by preventing infection or by delaying the disease, the type will be more and more prevalent as each generation comes to life.