REPRODUCTION 195 



Table 7. — Varieties and mating types in Paramecium bursaria 

 (Jennings; Jennings and Opitz; Chen) 



+ indicates that conjugation occurs; — indicates that it does not 



and Opitz (1944) found that mating type R (variety 4) conjugated 

 with E, K, L or M (variety 2), but all conjugants or exconjugants 

 perished without multiplication. Chen (1946a) made a cytological 

 study of them and observed that the nuclear changes which are 



