6oo 



H. S. 'Jennings 



sometimes Paramecia do not completely separate after division, 

 but remain united in chains. If we conceive of all the individuals 

 of each generation as thus forming a chain, each being in the posi- 

 tion that the method of transverse fission gives it, then on such 



Fig. 6 Diagram showing the position and relations of the spine of a in the sixth generation, when 

 thirty-two individuals are present. The individuals are conceived to have remained united, in the posi- 

 tions given them by the successive fissions. The spine would be found on the eleventh individual from 

 the anterior end of the chain (drawn with a hea\7' outline). 



a chain we would find but one spine, having a certain definite posi- 

 tion. Thus, in the sixth generation, where thirty-two individuals 

 were present, the spine would have been situated as shown in 

 Fig. 6, on the eleventh individual from the anterior end of the 



