SPOROZOA. 



INTRODUCTION. 

 Position of Sporozoa in the Animal Kingdom. 



Sporozoa are a class of parasitic organisms belonging to the 

 phylum Protozoa. In the Protozoa the body usually 

 consists of a single undivided mass of protoplasm, and these 

 organisms are consequently described as unicellular or non- 

 cellular. In other classes of the Protozoa the animals, 

 which may be free-hving or parasitic, move by characteristic 

 organs of locomotion such as pseudopodia, flagella or ciha : 

 but the class Sporozoa includes organisms which are entirely 

 parasitic, and as a rule are incapable of free locomotion. 

 Some of them, when immature, move about by means of 

 pseudopodia, but they never possess ciha or fiagelJa. All 

 are characterized by producing spores. 



Our knowledge of the Sporozoa commenced just over 

 a hundred years ago. In 1826 Dufour gave the first detailed 

 account of an organism, which he afterwards, in 1828, named 

 Gregarina. He found it in the ahmentary canal of several 

 species of Coleoptera, and later in the gut of the earwig. 

 Both he and Siebold, who investigated the genus m 1837 and 

 1839, failed to recognize it as a Protozoan. Schleiden, Henle, 

 and others recognized the unicellular nature of Gregarina, 

 but regarded it as an overgrown plant-cell, and it was only 

 as late as 1848 that Kolliker demonstrated the Protozoan 

 nature of the genus, described the formation of pseudonavicellse, 

 and inferred that they represented one method of propagation, 

 a view that was confirmed the same year by Stein. The 

 complete fife- cycle of a Gregarine was worked out much 

 later by Siedlecki (1899). 



In 1839 Hake pubhshed the earhest account of a Coccidian. 

 He described and figured the oocysts of Eimeria stiedse of the 

 rabbit's liver, but did not mterpret them as of parasitic origin. 

 Important observations on a Coccidian were pubhshed by 

 Kloss (1855), who described the organism now known as 

 Klossia helicina in the renal organ of the snail. Eimer (1870) 

 described parasites of the gut and the fiver of various animals, 

 including man, which have since been referred to the genera 



SPOR. B 



P^B - 9 1939 



