THE TELOSPORASIDA AND THE COCCIDIA PROPER 



247 



genus Merocystis, it is much more prob- 

 ably Adelea or Adelina, both of which 

 occur in arthropods, and it may well be a 

 parasite of some arthropod which the 

 pigs had eaten. 



FAMILY LANKESTERELLIDAE 



Members of this family are hetero- 

 xenous, with 2 hosts. Schizogony, game- 

 togony and sporogony all take place in a 

 vertebrate host. The sporozoites enter 

 the blood cells and are taken up by a 

 blood-sucking invertebrate (a mite or 

 leech). They do not develop in this host, 

 but are transferred to the vertebrate host 

 when the latter eats the invertebrate, or 

 possibly by injection. In the vertebrate 

 host, development takes place in the host 

 cells proper. The oocysts contain no 

 sporocysts, but have 8 or more sporo- 

 zoites, the number depending on the genus. 

 The microgametes have 2 flagella so far 

 as is known. There are 2 genera in this 

 family: Lankesterella, which occurs in 

 birds and amphibia, and Schellackia, 

 which occurs in reptiles. 



Genus LANKESTERELLA Labbe, 1899 



In this genus the oocysts contain 32 

 or more naked sporozoites. The vectors 

 are leeches or mites. 



The type species, and the only one 

 known for a long time, is L. minima, 

 a parasite of the frog. However, Lainson 

 (1959) recently showed that the genus 

 Atoxoplasma Garnham, 1950 is a synonym 

 of Lankesterella, enlarging the genus con- 

 siderably and clearing up a question which 

 has puzzled parasitologists for years. 



The parasites now known to be sporo- 

 zoites of Lankesterella are found fre- 

 quently in the lymphocytes and other blood 

 cells of wild birds. They had been thought 

 to be Haemogregarina or Toxoplasma, but 

 Garnham (1950) showed that they were 

 definitely not the latter and therefore 

 called them Atoxoplasma. 



The names and accepted species of 

 the genus are still in a highly confused 

 state (Laird, 1959; Lainson, 1959). 



Lankesterella adiei (Aragao, 1933) 

 Lainson, 1959 (syns. , L. passeris Raf- 

 faele, 1938; L. garnham i Lainson, 1959) 

 is a common parasite of the English 

 sparrow thruout the world. Lainson 

 (1959) found it in all of 99 adult and 150 

 fledgling English sparrows in England, 

 Manwell (1941) and Manwell et al. (1945) 

 reported that it was common in passerine 

 birds, and D. D. Myers (unpublished) 

 found it commonly in English sparrows in 

 Illinois. The sporozoites occur in the 

 lymphocytes and monocj^es, and often 

 cause a pronounced indentation of the host 

 cell nucleus. They are typically sausage- 

 shaped with rounded ends, stain weakly 

 and lack a well defined periplast, so that 

 it is often difficult to differentiate their 

 cytoplasm from that of the host cell. 

 Their nucleus is diffuse and granular, 

 with a tiny karyosome. They measure 4 

 to 5 by 2 to 4 fi according to Lainson (1959). 



The life cycle of L. adiei was des- 

 cribed (under the name L. garnliami) by 

 Lainson (1959). Schizogony takes place 

 in the lymphoid-macrophage cells of the 

 spleen, bone marrow and liver. There 

 are 2 types of schizont, one producing 10 

 to 30 (average 16) oval merozoites meas- 

 uring 4 by 2 (i , and the other producing a 

 smaller number of larger merozoites 

 measuring 6 by 3. 5|ll. Gametogony and 

 sporogony take place in the lymphoid- 

 macrophage cells of the liver, lungs and 

 kidney. The microgametocytes resemble 

 those of Eimeria and produce 60 to 100 

 microgametes. The macrogametes are 

 about 14. 5 /J, in diameter when mature and 

 produce a large but unspecified number of 

 sporozoites measuring about 3.6 by 1.8)i. 

 The vector is presumably the common red 

 mite, Dermanyssus gallinae, but Lainson 

 was unable to prove this because he had 

 no uninfected receptor birds. 



According to Lainson (1958), Lanke- 

 sterella may cause congestion and hemor- 

 rhage of the blood vessels and inflamma- 



