102 PROTOZOA 



of Coccidiidae, when free, usually possess two long ilagella, either 

 both anterior, or a very long one in front and a short one behind, 

 both turned backwards. 



The genus Coccidium affects many animals, and one species in 

 particular, C. cuniculi Eivolta, attacks the liver of young rabbits, 1 

 giving rise to the disease " coccidiosis." Coccidium may also 

 produce a sort of dysentery in cattle on the Alpine pastures of 

 Switzerland ; and cases of human coccidiosis are by no means 

 unknown. Coccidium-like bodies have been demonstrated in the 

 human disease, " molluscum contagiosum," and the " oriental 

 sore " of Asia ; similar bodies have also been recorded in smallpox 

 and vaccinia, malignant tumours and even syphilis, but their 

 nature is not certainly known ; some of these are now referred to 

 Flagellata (see p. 121). 



Closely allied to the Coccidiidae are the Haemosporidae, 

 dwellers in the blood of various cold-blooded Vertebrates, 2 and 

 entering the corpuscles as sporozoites or merozoites to attain the 

 full size, when they divide by schizogony; they are freed like those 

 of the next family by the breaking up of the corpuscle. The 

 merozoites were described by Gaule (1879) as "vermicles" 

 (" Wiirmchen "), and regarded by him as peculiar segregation- 

 products of the blood ; though Lankester had described the same 

 species in the Frog's blood as early as 1871, with a full recogni- 

 tion of its true character. His name, Drepanidium, has had to 

 give way, having been appropriated to another animal, and has 

 been aptly replaced by that of Lankesterella. The sexual process 

 of Karyolysus has been found to take place in a Tick, that of 

 Haemogregarina in a Leech, thus presenting a close analogy to 

 the next group, which only differs in its less definite form in the 

 active state, and in the lack of a cell-wall during brood- formation. 



Laveran was the first to describe a member of the Acysto- 



1 The schizont forms of some species, before the invariable alternation of 

 schizogony and sporogony had been made out clearly, were regarded as "mono- 

 genic" genera, under the names of Eimcria, A. Schn., and Pfeifcrella, Labbe ; 

 while those in which the formation of spores containing sickles had been clearly 

 seen were termed "digenic." Labbe's monograph, "Die Sporozoen," in the 

 Tierreich, is unfortunately written from this point of view, which had already 

 become doubtful, and is now demonstrated to be erroneous, chiefly by the labours 

 of Schaudinn and Siedlecki. 



2 A species has been described, however, in the blood of the Indian Gerbille 

 (Qerbillus indicus), completing the sexual process in the Louse of its host. A 

 figure of G. aegyptius will be found in Vol. X. (1902) p. 475. 



