192 PROTOZOOLOGY 



a class or caryonide (Sonneborn, 1939) are progeny of one of the two 

 individuals formed by the first division of an exconjugant and thus 

 possess the same macronuclear constitution. These classes were des- 

 ignated by Sonneborn (1938) as mating types. Soon a similar phe- 

 nomenon was found by several workers in other species of Para- 









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4. 









it _• ' . im. o _ • _i .*_, J 



Fig. 84. Mating behavior of Paramecium bursaria (Jennings), a, indi- 

 viduals of a single mating type; b, 6 minutes after individuals of two mat- 

 ing types have been mixed; c, after about 5 hours, the large masses have 

 been broken down into small masses; d, after 24 hours, paired conjugants. 



mecium; namely, P. bursaria (Jennings, 1938), P. caudatum (Gil- 

 man, 1939; Hiwatashi, 1949-1951), P. trichium, P. calkinsi (Sonne- 

 born, 1938) and P. multimicronucleatum (Giese, 1939). When organ- 

 isms which belong to different mating types are brought together, 

 they adhere to one another in large clumps ("agglutination") of 

 numerous individuals (Fig. 84, b). After a few to several hours, the 



