Notes on the Pathological Changes in the Organs of Birds Infected with Hæmocytozoa

Several authors have given brief descriptions of deposits of pigment found by them in the tissues of birds which had for some length of time been infected with h~emocytozoa. Danilewsky, in his "Para-sitologie Compar6e du Sang," in 1889, speaks of the changes in the hmmopoietie organs and describes macrophages containing pigment masses, parasitiferous and shrunken red corpuscles and the remains of parasites. Again, in 1890, he describes the blackening of the spleen and the enclosure of pigmented cells in large macrophages. He found also similar changes in the bone-marrow. Kruse (2) in the same year drew attention to the dark color of the spleen, although, owing to his lack of familiarity with the anatomy of birds, he was unable to decide whether or not the organ was enlarged. He found pigment enclosed in the large clear cells in the capillaries of the spleen, liver, lung and bone-marrow; he regarded this as an evidence of the acuteness of the process, since he argues that in a chronic infection the pigment would probably all be contained in fixed cells. Labb6 (1) in 1894 speaks also in a general way of the gross changes in the organs of infected birds. Our own observations on the pathological changes in the organs of birds infected with h~emocytozoa are based on the results of a study of the tissues of those birds whose blood has been described by Mr. Opie in the preceding paper (p. 79). In a series of abo¢lt 125 birds autopsies were made in all cases in which infection was found, and for the sake of control in a few which were free from infection. In