O ERNEST WARREN. 



tramia asperospora [Fritsch), and was originally described 

 by Bei'tram^ in 1892. It will be seen tliat tlie species about 

 to be described differs in some important characters from 

 B. asperospora; but for the present the generic name may 

 be retained, and the species w'ill be called after its discovei^er 

 — B e r t r a m i a kirk m a n i . 



(1) Structure and growth of the organism. — The 

 species of rotifer in which alone this parasite was found 

 lives in shallow pools among conferva, etc. It is by no means 

 a common species, but the percentage of parasitised indi- 

 viduals was exceedingly high. Out of some thirty-five speci- 

 mens collected and examined during the months of April, 

 May, and June about twenty infected individuals were 

 discovered ; that is, nearly 60 per cent, were infected. In an 

 allied species, Cop ens spicatus, which was very common in 

 the same water, the parasite was never found ; it appeared to 

 be confined to the rarer species. During the same period a 

 number of specimens were collected at Richmond, Natal, but 

 all these were non-infected. It would thus appear that the 

 disease is prevalent in the particular spot near Pietermaritz- 

 burg where the species has been found for several consecutive 

 years. 



The youngest stage found in the life-history of the parasite 

 occurred in only a single specimen of rotifer. The body- 

 cavity of the host contained some thirty irregularly-shaped 

 bodies, which were the youngest trophozoites discovered. 

 Some of these, the more curiously shaped ones in particular, 

 are shown in fig. 5. The smallest trophozoite in this rotifer 

 possessed two nuclei, and is shown in section in fig. 1. The 

 nuclei are relatively large ; they are provided with a definite 

 nuclear membrane and a karyosome. In the living condition 

 the general cytoplasm in this early stage is exceedingly hya- 

 line, and there is but little distinction between ectosarc and 

 endosarc. No amoeboid movements were observed in any 

 stage of growth of the parasite. 



' " Beitrage ziiv Kenntnis der Sareosporidien."" • Zool. Jalirb. Abth. 

 f. Anat.." Y. 



