FERTILIZATION 



619 



a union is made which involves an insecure adhesion of the bodies in 

 the anterior left peristomal region. The peristome is distorted by the 

 fusion, but the mouth continues to feed until it degenerates in the reor- 

 ganization process. 



While the majority of ciliates become attached along their ventral or 

 ventro-lateral margins and fuse anteriorly, several exceptions are note- 



Figure 146. A pair of Euplotes patella in conjugation. The micronuclei have under- 

 gone preliminary division and are now in the first meiotic division; the C-shaped macro- 

 nuclei are beginning to degenerate. (Turner, 1930.) 



worthy. Didhiium nasutum (Prandtl, 1906; Mast, 1917) and members 

 of the Ophryoscolecidae (Dogiel, 1925) join end to end anteriorly, the 

 latter forming an oral chamber by the juxtaposition of the two deep 

 peristomal pockets. Dogiel states that the conjugants are smaller than the 

 ordinary forms, owing to special progamic fissions. In Parachaenia myae, 

 Kofoid and Bush (1936) found conjugants attached by their posterior 



