CAUSE AND NATURE.—While the unborn foal (foetus) is in the womb of its mother, it is surrounded by enveloping membranes which constitute the afterbirth on delivery. These membranes are attached to the wall of the womb and are connected to the foetus by means of the navel-string (umbilical cord) which is provided with two arteries and a vein for the nourishment of the young creature and for the removal of its waste products. It also has a narrow canal (the urachus) which serves to remove the urine of the foetus; in fact the subsequently formed bladder takes its origin from a dilation of the urachus. Under normal conditions when the foal is born, respiration takes place, the umbilical arteries and veins become quickly blocked up, urine is discharged through the urethra (which communicates with the penis or vagina, as the case may be), the foal enjoys a separate existence and the wound caused by the division of the umbilical cord leaves a scar which is known as the navel. It is usually supposed that the germ of navel-string infection gains admittance into the body through the exposed surface before the wound is closed. However, I am of the opinion that the mother is the bearer of the infection in a great many cases for in the uterine secretions of mares whose foals fell with navel-string infection, the same characteristic germs were found as were present in the joints of the affected foals. The infectious material is, by the act of covering, conveyed from mare to mare, so that the mucous membranes of the womb becomes the habitat of the specific germ. By inoculation of these germs into the blood stream of foals an illness is produced which in the smallest particular cannot be distinguished from that arising in naturally affected foals. It is a strange fact that when the infected germs are transmitted by the mother, their presence does not produce any disturbance in her. This is a very common malady in most places. I have known several instances on particular farms where they were unable to raise either foals or calves, but if the mother were removed to another farm immediately after or before foaling, the foal or calf lived and was reared without difficulty, and although constitutional debility plays an important part, the presence of specific germs constituting an infected area is, I believe, the most important factor in producing this disease. According to my observation, about seventy-five per cent of the cases die within the first three weeks after birth. This high rate of mortality would be considerably diminished if proper treatment was adopted.