TELOSPORIDIA 129 



by possessing very great powers of multiplication, coupled with a 

 capacity for producing forms that serve for the transference of the 

 organisms to other hosts. These reproductive bodies, whether for 

 increase of numbers within one host or for transmission to another 

 host, are called spores. But, strictly, the term spore should be used 

 only in the latter connection, when a protective or resistant coat 

 known as a sporocyst envelops the body of the spore. 



The Sporozoa are widely distributed, occurring in various tissues 

 and organs of Annelids, Molluscs, Arthropods, and Vertebrates. 

 Their food, which is fluid, is absorbed osmotically. The life-cycle 

 of a Sporozoon may be completed within one host or may be dis- 

 tributed between two different hosts. 



The Sporozoa were divided by Schaudinn into two groups or 

 sub-classes, called (i) the Telosporidia, and (2) the Neosporidia. 



The Telosporidia are Sporozoa in which the reproductive phase 

 of the parasites is distinct from the growing or trophic phase, and 

 follows after it. The Neosporidia include Sporozoa in which growth 

 and spore-formation go on simultaneously. This classification is not 

 final, for certain exceptions and difficulties are already known with 

 regard to it. It is possible that the class Sporozoa is not a natural 

 entity, but should be replaced by two classes of equal rank, corre- 

 sponding in most respects with the Telosporidia and Neosporidia. 



The Telosporidia comprise the Gregarinida, the Coccidiidea, and 

 the Haemosporidia. Doflein combines the two latter orders into one 

 known as the Coccidiomorpha. 



The Neosporidia comprise the Myxosporidia, the Microsporidia, 

 the Actinomyxidia, the Sarcosporidia, and the Haplosporidia. 

 Doflein combines the first three orders into one, the Cnidosporidia. 



Sub-Class. TELOSPORIDIA, Schaudinn. 



Sporozoa in which the reproductive phases follow completion of 

 growth. 



Order. Gregarinida, Aime Schneider emend. Doflein. 



Knowledge of the Gregarinida probably goes back as far as the year 1684, when 

 Redi observed gregarines in the crab, Cancer pagurus. Von Cavolini (1787) found 

 them in Cancer depressus. The name Gregarina was created by L. Dufour (1828), 

 who observed masses of these organisms in the gut of insects of different orders. 

 Hammerschmidt (1838) and von Siebold found rich infestations in insects, while 

 Dujardin (1835) a d Henle described various genera from segmented worms. 

 Henle (1835) a l so observed cysts containing "navicellse" in the sperm-sacs of 

 segmented worms, and attention was drawn to his researches by the discovery by 

 von Siebold (1839) of" pseudonavkrellae" in the gut of Sciara nitidicollis. Up to this 

 time many workers considered the gregarines to be worms, but Kolliker (1845) 

 investigated many of them and maintained their unicellular nature, while Stein's 

 work (1848) showed the interrelation of the pseudonavicellas and the gregarines. 

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