312 THE SPOROZOA 



ORDER 7. Serosporidia, 1 L. Pfeiffer. 



This order was instituted by its founder for minute parasites observed 

 by him in the body-cavity (haemocoele) of certain Crustacea. The follow- 

 ing genera are referred here : 



Genus 1. Serosporidium, L. Pfeiffer, 1895. The type -genus of the 

 order contains several species of oval or rounded parasites which repro- 

 duce in two ways (1) By simple division ; (2) by forming a cyst within 

 which the parasite breaks up into numerous amoeboid germs. S. cypridis, 

 L. Pffr., from the body-cavity of Cypris sp., and other species from Cypris 

 wrens and Gammarus pulex. 



Genus 2. Blanchardina, Labbe", 1899 (nom. nov. pro Blanchardia, 

 Wierzejski, 1890). Amoeboid masses, which become cylindrical or sac- 

 like, and then of beaded form. Each bead becomes separated and forms 

 a cyst, at first fusiform, later oval or spherical Further reproduction 

 not observed. Unique species B. cypricola, Wrzski., from body-cavity of 

 Candona Candida and Notodromas monacha. 



Genus 3. Botellus, Moniez, 1887. Elongated ovoid tubes, containing 

 halter-shaped spores, each with two nuclei. B. typicus, Moniez, from 

 generative organs and haemocoele of Geriodaphnia reticulata, Chydorus 

 sphaericus, and Moina rectirostris. Two other species from Cypris and 

 Daphnia. 



Genus 4. Lymphosporidium, Calkins, 1900, for L. truttae, Calkins, 

 parasite of the brook trout, Salvelinus fontinalis. The trophic phase 

 of the parasite commences in the lymph as a minute germ which grows 

 into an amoeboid body. The amoebula then invades the muscle-bundles 

 of the intestine and other organs. In this situation the amoebula grows 

 into the adult organism, which has its protoplasm full of chromatin 

 granules, forming a distributed nucleus. Spore-formation commences by 

 the parasite rounding itself off and being set free in the lymph or other 

 cavities (gall-bladder, intestine), and by a concentration of the chromatin 

 into several masses in the interior of the cell, each such mass becoming a 

 spore. The spores are carried to all parts of the body in great numbers, 

 blocking the lymph -passages, and causing sores and ulcers, and finally 

 bringing about the death of the host. When set free the spores infect 

 fresh hosts, probably by way of the digestive tract. In this situation 

 they develop further, each producing eight germs or spprozoites, which 

 become the starting-points of fresh generations of the parasites. The 

 spores may, however, develop in the internal cavities of the host in which 

 they were produced. This parasite causes extremely virulent epidemics. 



ORDER 8. Exosporidia, Perrier. 



The order Exosporidia was founded by Perrier to include the peculiar 

 organism, ectoparasitic upon certain aquatic Arthropoda, to which Cien- 

 kowsky gave the generic name of Amoebidium. Many authorities con- 



1 The name was written Serumsporidia by Pfeiffer, and corrected to the more 

 euphonious spelling, here adopted, by Wasielewski. 



