The Effect of repeated Bleedings on the Blood Constituents of Immunised Horses

(1) From a horse injected with sheep's red cells three months prior to the first bleeding and in a condition of constant haemolytic titre 122 litres of blood were taken in a period of 11 months. The horse's condition remained good throughout and has markedly improved during the year.(2) The net result was that the haemolytic titre during that time fell only to about 66% of its original value, the leucocytes to about 66%. haemoglobin scarcely at all, while the specific gravity of the blood and total protein have increased, the former by 10% the latter by 5%;.(3) There was no relationship between the total number of leucocytes and the amount of antibody. The differential count showed an increase of 12% in the polymorphonuclear and a decrease of 12% in the mononuclear cells, these figures being not very far outside the experimental error. The eosinophile and mast cells showed no marked alteration in number, size or staining reactions.