Jennings, BeJiavior of Paranicciiun. 481 



and in passing its posterior end drags across the oral surface o^ 

 the latter. Thereupon they stick together, and a struggle en- 

 sues, each individual trying to pursue its forward course and 

 not succeeding, till one finally drags the other one backward 

 (Fig. 13, at the upper left hand corner). The second speci- 



/'/;''• 13- Irregular adhesion of individuals, observed iij cultures of Para- 

 mecia in which conjugation was taking place. These groups move about irregu- 

 larly, remaining attached, in spite of the struggles of the individuals. 



men may be dragged about through the water or over obstacles 

 of all sorts, till finally the adhesion gives way and they sep- 

 arate. Specimens thus become adherent in every possible way, 

 provided merely that some part of the oral surface of one of 

 the individuals enters into the adhesion. Many such cases are 

 clearly not early stages of any ordered conjugation, and they 

 often separate after one individual has been dragged about for 

 some time much against his struggles. 



Again, often more than two individuals thus adhere ; 

 groups of three, four or five are seen, adhering in all sorts of 

 irregular ways, and apparently struggling to free themselves. 

 A number of such cases of irregular adhesion are shown in 

 Fig. 13, from a culture in which conjugation was taking place 

 freely. It is evident that such groups as are shown in this fig- 

 ure cannot be interpreted as due to any will or desire of the 



