slain bird, and in the running water, and sprinkle the house seven times: and he shall cleanse the house with the blood of the bird, and with the running water, and with the living bird, and with the cedar wood, and with the hyssop, and with the scarlet: but he shall let go the living bird out of the city into the open field: so shall he make atonement for the house: and it shall be clean." There has been much debate as to what we are to understand by the leprosy in the garment or in a house. Was it an affection identical in nature with the leprosy of the body? or was it merely so called from a certain external similarity to that plague? However extraordinary the former supposition might once have seemed, in the present state of medical science we are at least able to say that there is nothing inconceivable in it. We have abundant experimental evidence that a large number of diseases, and, not improbably, leprosy among them, are caused by minute parasitic forms of vegetable life; and, also, that in many cases these forms of life may, and do, exist and multiply in various other suitable media besides the fluids and tissues of the human body. If, as is quite likely, leprosy be caused by some such parasitic life in the human body, it is then evidently possible that such parasites, under favourable conditions of heat, moisture, etc., should exist and propagate themselves, as in other analogous cases, outside the body; as, for instance, in cloth, or leather, or in the plaster of a house; in which case it is plain that such garments or household implements, or such dwellings, as might be thus infected, would be certainly unwholesome, and presumably capable of communicating the leprosy to the human subject. But we have not yet sufficient scientific observation to settle the question whether this is really so; we can, however, safely say that, in any case, the description which is here given indicates a growth in the affected garment or house of some kind of mould or mildew; which, as we know, is a form of life produced under conditions which always imply an unwholesome state of the article or house in which it appears. We also know that if such growths be allowed to go on unchecked, they involve more or less rapid processes of decomposition in that which is affected. Thus, even from a merely natural point of view, one can see the high wisdom of the Divine King of Israel in ordering that, in all such cases, the man whose garment or house was thus affected should at once notify the priest, who was to come and decide whether the appearance was of a noxious and unclean kind or not, and then take action accordingly.