132 ANIMAL PARASITES. 



Eixford and Gilchrist ' have described in detail two cases of proto- 

 zoan (coccidoidal) infection of the skin and other organs, making a care- 

 ful comparison between these and organisms somewhat resembling them 

 which have been found in various skin lesions. 



4. Sarcosporidia. In this order of the Sporozoa the usually elongated, 

 slender early stage is found in between the muscle fibers and bundles of 

 vertebrates mouse, hog, and, in a few instances, in man. These are 

 commonly known as the " tubes of Miescher" or "of Bainey." Reni- 

 forin or falciform spores are developed. The adult forms are spheroidal 

 or elongated. The life cycle is not well known. 2 



5. Hcemosporidia. These parasites of the blood form a large group 

 occurring in the corpuscles or plasma of vertebrates amphibia, reptiles, :i 

 birds, and mammals. Some forms are among the most important of the 

 protozoan parasites of man. They are of small size ; the adult form is 

 motile. One stage in the life cycle is passed in the blood of the verte- 

 brate host. Another stage or cycle may be passed in the body of some 

 insect, acting as an intermediate host. 



Among the mammalian haemosporidia we may mention the hsematozoa 

 of malaria and the haernatozoon of Texas fever. 



The characters of the malarial haematozoon, for which the mosquito 

 acts as intermediate host, are described in detail 011 page 279. 



The hsematozoon inducing Texas fever in cattle was discovered by 

 Theobald Smith and called Pyrosoma bigeminum. In one stage it is a 

 minute pyriform organism occurring often in pairs in the red blood cells 

 of its host. Free forms have been found in the blood. While its life 

 cycle has not been completely worked out, Smith and Kilbourne showed 

 that a cattle tick acting as an intermediate host transmits the parasite 

 through her eggs and larvse. It is through these young ticks that fresh 

 cattle become infected. 4 



In 1902, Wilson and Chowning 5 described the occurrence of ovoid bodies in the red 

 blood cells of persons suffering from the so-called "spotted fever" of Montana. These 

 bodies in fresh blood showed amoeboid movements. These observations have been con- 

 firmed by Wesbrook and by Anderson. The infection is believed to occur through the 

 bites of ticks and the disease has been, therefore, called also "tick fever." Further 

 study is required before the etiology of this disease and the intervention of the tick can 

 be regarded as established. 



'Johns Hopkins Hospital Reports, vol. i., p. 209, 1896; Bibliography. 



4 For a study of the production of sarcosporidia in the mouse see Theobald Smith. 

 Trans. Assn. Am. 1'hys., vol. xvi., p. 576, 1901. 



:! See lAingmfinn, " Ha'inosporidia in American Reptiles and Batrachians " N. Y 

 Med. Jour., January 7th, 1899. 



4 For a summary of observations on Texas fever (Haenioglobiuuria of Cattle) see 

 Kowet. in Kolle and Wassermann's "Handbuch der Mikroorganismen," Bd. i., p. 841, 

 I>ibl. 



5 Wilson bud Chowning Jour. Infec. Dis., vol. i., p. 31, 1903. 



