176 PROTISTS AND DISEASE 



the parasite Karyoryctes found by Calkins in 1904 in the 

 macronucleus of Paramaecium aurelia. 



Some of Dangeard's illustrations are shown in Fig. 50. 

 The parasites enter the nucleolus of their host, Amoeba 

 verrucosa. They have obvious nuclei from the first. In 

 the grown parasite, d, the nuclei are of fungal type and are 

 like those shown in Olpidiopsis in Fig. 16, e. The spores are 

 liberated by disintegration of the remains of the host- 

 karyoplasm ; this occurs only when the parasite has com- 

 pleted its development. Dangeard concluded that Nucleo- 

 phaga is a vegetable rather than an animal protist because 

 it leaves no food-remains. 



Turning now to Karyoryctes as shown in Fig. 51, the 

 young parasites as in c and d have no centrally placed 

 nucleus, but a thickening at the side which gives a " signet- 

 ring " look. The spores as shown at a germinate by forming 

 a vacuole and the protoplasm grows into it in plasmodial 

 form, still without nuclei. Another mode of reproduction 

 in Karyoryctes, e, is not seen in Nucleophaga, but is similar 

 to that shown below, Fig. 54, 18, 19, in a Plassomyxa of a 

 sarcoma. The reticulate body, /, was also termed residual, 

 but its points of chromatin recall the chromidial stage of 

 the direct sporangium of Synchytrium. 



No two related protists could well be less alike than 

 Nucleophaga and Karyoryctes : the former is a Chytridian, 

 the latter one of the Plassomyxineae. 



The accomplished protozoologist has done better than 



