THE ZOOLOGIST 



No. 872.— February 15th, 1914. 



PAEASITISM IN EELATION TO BIRDS. 

 By H. Victor Jones 



(Honours man in Zoology, and late Quasi Demonstrator in Zoology at the University 

 College, Bangor, North Wales.) 



(Plate I.) 



Parasitism is a subject which at the present time is offering 

 a wide field of investigation to biologists, especially so to 

 bacteriologist and parasitologist proper. 



Upwards of thirty Protozoa — representing the main division of 

 the group — are known at some stage or other of their life-history 

 to be parasitic in the human body ; the presence of which causes 

 diseases of a most vicious nature, such, for example, as " sleeping 

 sickness," due to Trypanosoma gambiense. The so-called Leish- 

 man-Donovan body, the parasite of dum-dum fever or spleno- 

 megaly, and many others of a similar nature may be cited. 



No less important is the parasitism as exhibited by the 

 phyla Platyhelminthes and Nematohelminthes. These phyla 

 show different degrees of parasitism, as will be seen from the 

 following classification : — 



Phyla. 



Family. 



Degree of Parasitism. 



Platyhelminthes. 



Turbellaria. 

 Trematoda. 

 Cestoda. 



All free-living. 

 | Endo-parasitic. 

 {Ecto-parasitic. 



All enclo-parasitic. 



These families are undoubtedly connected with one another, 

 Zool. 4th ser. vol. XVIII., February, 1914. e 



