HALTERIDIUM AND PIROPLASMA 653 



(Gulex fatigans), by which the infection is transmitted to other 

 birds. 



Halteridium Danilewskyi 



This is an elongated, curved parasite (also known as Hwmo- 

 proteus or Hcemamceba Danilewskyi), found in the red corpuscles 

 of certain birds (pigeon, crow, etc.), and embracing the nucleus 

 (Plate XXX, b). By some it is included among the malaria- 

 like parasites (Plasmodium). At an early stage it much resemble 

 the proteosoma, but as it grows it becomes elongated, pigment- 

 granules appear, and are either scattered throughout the proto- 

 plasm or collect in two groups, one at each extremity. Finally, 

 the parasite occupies nearly the whole of the corpuscle, dislocating 

 its nucleus. The fully grown parasites may be differentiated 

 into two forms, one of which remains almost completely un- 

 stained when treated with methylene-blue, the other staining 

 deeply with this dye (Opie). When the blood is withdrawn, the 

 corpuscles disintegrate and liberate the contained parasites, 

 which assume a circular outline, and a certain number become 

 flagellated. It is only the non-staining form which becomes flagel- 

 lated. These two varieties of the parasite are the male and female 

 cells respectively, and the fertilisation of the female cell by a free 

 flagellum has been actually observed by MacCallum. 1 It can 

 hardly be doubted that the development of the fertilised cells 

 takes place in some insect, but the definitive host has not yet 

 been discovered with certainty. 



The presence of these parasites induces rise of temperature, 

 deposition of melanin, and changes in, and enlargement of, the 

 spleen and liver, analogous to those occurring in malaria in man. 



Somewhat similar parasites are frequent in the blood of the 

 lower vertebrates (see Plate XXXI, b). 



The Piroplasmata 2 



Syn. Pyrosoma, Babesia. 



The Piroplasmata form a somewhat anomalous group, but are 

 usually included in the Haemosporidia of the Sporozoa. They 



1 Journ. Exper. Med., vol. iii, 1898, pp. 79, 103, 117. 



2 See Hewlett, Trans. XlVth Internal. Cong, of Hygiene, Berlin, vol. ii, 

 1908, p. 146 ; Minchin in Allbutt's System of Med., ed. 2, vol. i, pt. 2, p. 86. 



