“Indeed,” one of the critics has said, “you vaunt the progress of medical science at a time when you have to confess that it has failed to cure tuberculosis, one of the gravest of the infectious diseases, which alone causes the death of a sixth part of the human race.” It is true that the infectious nature of this scourge was announced by Villemin more than forty years ago. Twenty years have passed since Koch, the German bacteriologist, discovered the microbe that produces not only the ordinary form of pulmonary consumption but all other varieties of tuberculosis. And we are still ignorant of any remedy for the disease. In all the bacteriological institutes and laboratories search is being made for some vaccine or serum or medicament which will arrest a disease that in many cases nature herself cures. But the results amount practically to nothing. This is certainly a good example of the failure of science. None the less a closer examination shows that even with the knowledge already gained we could deal with tuberculosis in a manner more efficacious than is the existing practice. When the infectious nature of the disease had been made known, before waiting for the discovery by Koch of the actual bacillus, we should have employed all the known modes of destroying infectious matter. In spite of all that has been said and written on the subject, people still spit on the floors of omnibuses and cars and on street pavements. Tuberculosis is propagated not because of the failure of science, but because of the ignorance and stupidity of the population. To diminish the spread of tuberculosis, of typhoid fever, of dysentery, and of many other diseases, it is necessary only to follow the rules of scientific hygiene, without waiting for specific remedies. Although the science of to-day is sufficiently armed against the diseases commonly known as infectious, the case is very different with some other affections, among which the chief place is taken by malignant tumours, or cancers, in the most general sense of the word. There are few maladies more terrible, for they practically never disappear spontaneously, and surgery can remove them successfully only if they have been recognised at an early stage. Every year a number of persons, old and young, die victims of malignant tumours, and it is even possible that cancer is more prevalent now than in former times. It has been suggested that the increase of cancer is due to the greater longevity among modern races, and as malignant tumours are most common in old persons, it may well be that the prolongation of life has given this disease a larger field. However, even allowing for this, it is probable that there is a real increase of cancer.