DEVELOPMENT OF SPERMATOBIUM. 27 



equal or unequal parts, not separated by regular division 

 fields. 



Radiation or Budding. The nucleus branches out, 

 forms nodes, which latter by retraction of filaments be- 

 come independent nuclei — Spermatobium. 



Sporulation. The nuclear plasma become by the aid 

 of achromatic filaments divided into numerous equal parts, 

 which, through the bursting of the caryotheca, are set 

 free and form independent nuclei — Foraminifera. 



Haemagregarina nasuta n. sp. Figs. 50 to 64. 



This form infests the walls of the blood-vessels and 

 surrounding mesenterium of Eclipidrilus frigidus in 

 enormous numbers. The cysts lie so closely that they 

 frequently touch each other, and totally obscure the 

 structure of the tissue of the host, to such an extent that 

 there appears to be more of the parasites than of the 

 tissue. I have only found the parasite in specimens of 

 Eclipidrilus from the locality on the middle fork of King's 

 River, California, at an altitude of about 11,000 feet, 

 while the Eclipidrili found at the lower altitude and in im- 

 pure water were entirely free both from H^magregarina 

 and Spermatobium. 



Although the host from the former locality were in- 

 fested at the rate of thousands, none contained protozoa 

 of different stages of development. I could only observe 

 the fully developed form, all cysts and all spores being 

 absent, the more to be regretted as related forms are only 

 imperfectly known. The relationship of Hcemagregarina 

 nasuta must therefore remain in doubt, and my rea- 

 sons for classing it with Haemagregarina depend alone 

 upon the appearance of the adult form as well as upon 

 its habitat. As is well known, Hsemagregarinas are 

 principally known through Danilewsky's description of 



