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confined to these. In fact there can exist no doubt in the mind of the morbid an- atomist, who has performed a few necropsies on the bodies of these diseased animals, that he has before him, a disease of a decided septicemic nature, the pathological appearances of which are chiefly characterised by the occurrence of widespread and multiple hæmorrhages into the organs and tissues, and of necrosis and ulceration more particularly in certain parts of the alimentary system.

The bacteriological enquiry into the nature of the exciting agent of this disease has yielded most satisfactory results. As will be described presently, this investigation has clearly shewn the disease to be distinctly septicemic in nature, and excited by the growth in the blood, organs and tissues, and the excrement and discharges of the infected animal of a definite species of micro-organism which possesses certain well marked morphological and biological characteristics.

This micro-organism can be isolated from every case of the disease either intra-ritam or post-mortem. The latter method of obtaining the micro-organism in pure culture is purely a question of careful bacteriological technique, the causative agent being present in considerable numbers in the different fluids and tissues of the dead animal. The most certain results are attained by the preparation of plate cultures from the lymphatic glands, more particularly from those which pre- sent a deeply hæmorrhagic appearance.

The demonstration of the micro-organism during life is a procedure of much greater difficulty. The discharges from the eyes, nose, rectum and vagina certainly contain the organism in considerable quantity, but owing to the presence of numbers of other micro-organisms in these excretions, its isolation is requiring of much technical skill. Further, films of blood obtained from the ear and prepared by Ross' method, occasionally show one or two typical micro-organisms. Their microscopic demon- stration in drops of blood and their successful cultivation from the blood stream during life are by no means constant factors. Indeed it would appear that the presence of the micro-organism in the circulating blood is not demonstrable during all periods of the disease. There is reason to believe that towards the end of the fatal form of the disease and more particularly during the agonal period, the micro- organism can be demonstrated with a much greater degree of certainty.

Again, in the discharge resulting from the occurrence of complications and sequelae of this disease, the micro-organism has been recovered in almost pure culture. In one instance of the chronic form of this disease, in which death resulted from the presence of miliary abscesses in both lungs, the micro-organism was obtained in almost pure culture from one of these pus foci.

In several other instances, subcutaneous abscesses resulted from experimental inoculation. In these the micro-organism was constantly present, although rarely in pure culture.

These remarks clearly emphasize the septicemic nature of the disease, a morbid process called forth by the growth in the blood stream and tissues of a particular micro-organism of which the following is a description.

Microscopic Appearances.

It is a short rod. Its length is rarely twice its breadth. It is extremely minute and frequently great difficulty is experienced in dertermining its rod-shaped nature. In films, the micro-organism appears at the first glance to be a micro- coccus or a diplo-coccus, but careful scrutiny shows that it is really a short bacillus with rounded ends and flattened extremities. When one end is pointed towards the observer the micro-organism appears to be a coccus. When the bacillus gives the appearance of a diplo-coccus. this illusion is due to the fact that the central por- tion of the rod remains unstained. This central part is contained within two delicate stained lines the walls of the rod-the whole giving the appearance of two juxta posed cocci. Its exact shape varies. It most frequently appears as an oval shaped rod, but coccoid and biscuit-shaped forms are met with.

This "bipolar staining" is by no means confined to any one species of micro- organism.

The micro-organism is found for the most part lying free in the plasma be- tween the leucocytes and red blood corpuscles. Rarely it is enclosed in the white blood cells. In the blood the individual rods are usually isolated, but in the spleen, hæmorrhagic lymphatic glands, etc., the bacilli are often united into small clumps- staphylo-coccoid in appearance.