DEVELOPMENT OF SPERMATOBIUM. 25 



in Spermatobium are found numerous microsporogonia of 

 nearly equal and very regular size as in Klossia. The 

 adult Spermatobium differs from Monocystis in its general 

 form. The pointed apices and epimerit are not seen in 

 Spermatobium, which is more regular, oval, globular or 

 slightly lunate with rarely projecting apex. The ciliated 

 covering, consisting of abnormally developed spermato- 

 gonia of the host, found in Monocystis are not seen in 

 Spermatobium. 



Finally, the form and structure of the nucleus and nu- 

 cleolus in Spermatobium agrees more with those of Klos- 

 sia than with those of Monocystis. 



The life history of Spermatobium is shortly as follows : 



RESUME. 



The young Spermatobium is intracellular parasitic in 

 the spermatogonium of the hosts Eclipidrilus and Phoeni- 

 codrilus, but it leaves these cells before the spermato- 

 blasts have begun to grow. The free form is shuttle- 

 like, later ovoid and finally globular, with extremely 

 prominent nucleus and nucleolus. In the cytoplasm of 

 the Spermatobium the cytospheres gradually develop at 

 the expense of or from the other element. 



The macronucleus, at first globular, becomes later ir- 

 regular, and finally diffuses itself all through and between 

 the cytospheres, forming at first nodes which later change 

 into new secondary nuclei equidistant from each other. 

 The cytospheres group themselves around these micro- 

 nuclei, which latter again divide by caryokinesis, thus 

 forming at first microsporogonia, then sporoblasts. The 

 sporoblasts develop first into shuttle spores. Pseudona- 

 vicella spores are also found. 



A division of the adult takes place sometimes, probably 

 caused by the accumulation of a too large quantity of nu- 



