SPOROZOA II 



and the cell contents have been shown in rare instances 

 to undergo division into spores. 



Reproduction. Sexual reproduction by the conjugation 

 of two cells which resemble each other. 



(2) Coccidia. Of a spherical or oval shape, and con- 

 tained in definite cyst walls when mature ; only the 

 youngest forms are motile. Fecundation by the con- 

 jugation of dissimilar cells. They are parasitic in cells 

 of warm-blooded animals and invertebrates, and fre- 

 quently form massive tumours. They have been described 

 in man, but little is known at present of human diseases 

 caused by them. Very common in rabbits. 



FIG. 2. Piroplasmata. 



(3) Hcemosporidia or Hcemocytozoa. Parasites of the 

 red blood corpuscles of warm-blooded animals; do not 

 form cysts in such hosts ; are parasitic throughout their 

 whole existence, the sexual phase taking place in inverte- 

 brates, e.g., insects or ticks. The young forms have 

 active amoeboid movement. They are divided into two 

 main groups : 



(a) Hcemamocbce, which form pigment, and usually 

 divide into a large number of spores. The definitive 

 hosts are mosquitoes. 



(6) Piroplasmata (fig. 2), which do not form pigment ; 

 divide into two or more young parasites. Ticks are the 

 definitive hosts. Piroplasmata have been described in man, 

 probably erroneously ; common in cattle, sheep, horses, 

 dogs, &c., and usually lead to extensive blood destruc- 

 tion, e.g., Texas fever in cattle, and haemoglobinuria in 

 sheep and dogs. Careful search has been made in men 

 in cases of blackwater fever for piroplasmata, but with 

 negative results. 



