24 PROTOZOA AND DISEASE 



on the other hand, they regard a a bacterium. It must, however, be 

 remembered that the disease with which this * spirillum ' is associated 

 is markedly cyclic or paroxysmal in its character, and this fact 

 suggests a protozoan rather than a bacterial cause ; moreover, should 

 it be finally proved that the bed-bug is a necessary intermediary in 

 spreading relapsing fever, this again strongly suggests protozoa as 

 the causal agents. 



Trypanosoma Nocttice. 1 



The great importance of trypanosome disease makes it necessary 

 for us to consider those of the many brilliant contributions to 

 zoology made by the late Fritz Schaudinn that bear on this subject. 

 No modern investigations have a wider application than those of his 

 that deal with some parasitic flagellates in birds. Certain forms of 

 parasitic protozoa occurring in the red and others in the white blood- 

 corpuscles and erythroblasts of birds had long been familiar under 

 the names of halteridia and leucocytozoa respectively. Schaudinn, 

 working at Rovigno, in Southern Italy, on the blood of the small 

 stone owl, A thene noctua, which is common there, found that these 

 parasites constitute but one phase of a varied life-cycle of two 

 different parasites, the T. noctuce and Sp. Ziemanni, and that in 

 the case of each of these parasites only part of the life - cycle 

 is passed in the blood or other tissues of the bird, the other 

 and biologically the more important part being completed in the 

 common gnat, Culex pipiens. Thus, these parasites, like plasmodium 

 (the haematozoon of malaria) and proteosoma, the life-cycle of which 

 was worked out by Ross in birds, require intermediate hosts for the 

 completion of their life-cycles. A few of the facts observed in 

 T. noctuce may now be referred to. 2 



1 In the course of time some modifications of Schaudinn's views are to be 

 expected, but his observations maybe taken as giving a correct general impression, 

 and his description of details of structure may be relied upon. 



2 The wide range of forms assumed by the parasites (parasitic adaptation) and 

 the corresponding changes in nuclear structure can only be hinted at here. The 

 original paper must be consulted for details : F. Schaudinn, in Arbeiten aus dem 

 Kaiserlichen Gesundhei'lsamte, Bd. xx., 1903 ; or H. M. Woodcock's digest of it 

 in the Quart. Journ. Microsc. Science, 1906. 



