Diversity Produced by Conjugation 157 



bcr of diverse combinations of the characters of the two par- 

 ents, as shown in Figure 43a, a, b, c, d. Pascher (1918) 

 gives a table of the various combinations found in the four 

 sets of individuals in comparison with the characteristics of 

 the parents A and B, as follows: 



Form Membrane Papilla Chromatophore Eyetpot 

 Parent A pear-shaped delicate none lateral linear 

 Parent B spherical coarse present basal broad 



The offspring a and d resemble very closely the two par- 

 ents respectively, while the types b and c show characters of 

 both the parental forms. This is the same sort of result 

 which we find in the Mendelian inheritance of higher organ- 

 isms. It is a demonstrated fact, therefore, that in the 

 Protozoa, as in higher forms, conjugation results in bi- 

 parental inheritance. 



Observe also that besides producing resemblance of par- 

 ents to progeny or of progeny to one another, conjugation 

 causes stocks or races or families to arise which are diverse 

 in their hereditary characters from either of those from 

 which they took origin. This is evident in Chlamydomonas ; 

 6 and c show diverse combinations from those found in 

 either of the parents, and these diversities are perpetuated 

 in their propagation by fission. In Paramecium, from a 

 single race all having the same hereditary characters 

 there may arise by conjugation many races with diverse 

 hereditary characters. 



What this means will best be illustrated from an actual 

 experiment (from Jennings, 1913). We begin with a set of 

 individuals all alike, all derived by fission from a single 

 parent. We study their rate of fission ; taking 174 separate 



