Page:Popular Science Monthly Volume 48.djvu/832

750 mentioned being diseases of lower animals which, may be transmitted to man. And in tuberculosis and glanders affecting domestic animals we have still another method of establishing the diagnosis in suspected cases. This is by the subcutaneous injection of a proper dose of a filtered culture of the specific pathogenic bacteria. These filtered cultures, containing the soluble toxic products developed during the growth of the bacillus, are known in the one case (tubercle bacillus) as tuberculin, and in the other (glanders bacillus) as mallein. The effect is similar in each case. When an animal infected with tuberculosis receives a suitable dose of tuberculin a characteristic febrile reaction is produced. In the non-infected animal this reaction does not occur. The same is true as regards animals infected with glanders which receive a dose of mallein. This test of infection is now extensively used both in this country and in Europe with very satisfactory results. The importance of an early recognition of these chronic infectious diseases is apparent. The danger from infected animals is not limited to the extension of the disease to others of the same species, but in tuberculosis those who consume the milk are exposed to the danger of infection, especially in cases where the udder of the animal is the seat of a tubercular infection.

I have by no means exhausted my subject, and an attempt to do so would probably exhaust the patience of my audience. In conclusion, I would say that the painstaking laboratory work which has led to the important practical results referred to is still being prosecuted with unabated vigor, and without doubt we may look for further valuable additions to our knowledge. These, together with a wider appreciation of the present status of this department of scientific investigation, can not fail to add largely to the practical results which will hereafter be achieved in the field of preventive medicine and of specific therapeutics, and in agriculture, in the dairy, etc., as heretofore indicated.

Prince of Monaco recently reported to the French Academy of Sciences on the results of his deep-sea dredging expedition of 1895, from Portugal to the Azores and back to the English Channel. The dredgings were carried to the depth of forty-two hundred metres, where weirs were deposited; and numerous soundings were made, some of them as far down as five thousand metres, and specimens of the water drawn up. Fine captures weie made in the weirs from fifteen hundred metres, in which echinoderms, mollusks, and fishes were plentiful. Thus, three hundred and fifty-five animals were taken in twenty-four hours in the same net three hundred of them fishes, large red shrimps, and cephalopods. Besides the usual fauna of such profundities, crayfishes eighty centimetres long and superb holothurias of forty-six centimetres were drawn up from the depth of four thousand metres.