On Nag ana, or Tsetse Fly Disease. Ill 



B. Lymphatic (Uml*. 



In the rat the superficial lymphatic glands may be readily examined 

 by piercing them with fine capillaries or sharp needles ; they may also 

 be excised and examined more thoroughly. Although a considerable 

 number of observations have been made by these means, and also after 

 killing the animals at various periods after inoculation, we wish to 

 speak somewhat guardedly, since the appearances are not quite con- 

 stant. Moreover, we are at present unable to be certain that unrecog- 

 nised developmental forms have not been overlooked. 



By the study of the right inguinal glands after subcutaneous inocu- 

 lation in the right thigh, we find that the hsematozoa are present from 

 one to three days before they are discoverable in the blood (taken from 

 the ear or right leg). Again, they may be very abundant in the gland 

 when they are still scanty in the blood. Moreover, the number in the 

 blood may increase, whilst that in the gland decreases. In these 

 earlier stages the hsematozoa may be extremely numerous, forming 

 tangles and clusters in the lymph gland, whilst only a few scattered 

 ones are to be found in the blood. The first appearance of hsematozoa in 

 the gland of the other side is apparently associated with their appear- 

 ance in the blood. 



The observations, fewer in number, which have been made upon 

 guinea-pigs, also point to a multiplication in or about the nearest chain 

 of lymphatic glands in the first instance. 



We have not yet determined whether these haematozoa pass 

 directly into the blood through the local blood vessels, or whether 

 they are distributed by means of lymphatic paths into the main 

 circulation. 



The animals may appear comparatively well whilst large numbers of 

 parasites are present in their blood and glands, this is especially the 

 case with rats and guinea-pigs. On the other hand they may be 

 seriously ill whilst the hsematozoa are scanty in their blood; this 

 obtains usually in rabbits, in which animals, as already stated, the 

 glands do not become so much enlarged, and it is possible that the 

 main effect of the parasites is borne by other organs. For instance, at 

 times the bone-marrow has shown the presence of hsematozoa, although 

 search in other organs and in the blood proved negative. 



After death in the various animals, haematozoa are to be found in 

 most cases in the bone-marrow and spleen. The adult hsematozoa may 

 l^e common in these situations when but few are present in the blood ; 

 but this is not constant, for the reverse may be the case. Multiplica- 

 tion of the parasites certainly takes place in the lymphatic glands (rat) 

 as well as in the infected area of connective tissue ; it may also occur 

 in the above-mentioned organs as well, and perhaps too in the blood, 

 but of this we have no certain evidence. 



