INHERITANCE IN ABNORMALITIES 409 



the numbers of the thirty types that appeared among: the abnor- 

 mals of this experiment and their frequencies. 



Likewise in the abnormals of Experiment 3 there was less 

 diversity of type than in those of Experiment 1. Table 4 gives 

 the numbers of the 27 types observed and their frequencies; 91 

 per cent of all the abnormals of Experiment 3 were of five types 

 (22, 26, 27, 30, 39). 



The lessened diversity of type observed in the experiment 

 with the members of a pure line (Experiment 2) as compared 

 with the members of a wild culture (Experiment 1) is just what 

 we might expect from the constitutions of the tvv^o groups. The 

 wild culture probably contained many very diverse stocks; the 

 conjugants probably were widely different in their gametic con- 

 stitutions; so that there is the greatest possible opportunity for 

 variation among their progeny. But all the members of the 

 clone used in Experiment 2, by the theory of the pure line, have 

 identical gametic constitutions. This may be and probably is 

 highly heterozygous; but the diversity possible to the progeny 

 of the different conjugants is limited by this heterozygosity. 

 In Experiment 1 the diversity is limited only to the characters 

 possible to 262 members of the species Paramecium caudatum, 

 since every conjugant might possibly be different from every 

 other; in Experiment 2 however this diversity is limited to the 

 characters possessed by one individual Paramecium (the pro- 

 genitor of the pure line used) and their possible recombinations. 

 This fundamental difference in the constitutions of the two groups 

 is very probably a cause of the production of greater diversity 

 in form, and in the size, shape, and length of life of the indi- 

 viduals that never divided, mentioned on page 393. 



TJie individuals used in the third experiment cannot be con- 

 sidered in this discussion, since they were derived from a small 

 culture kept for some time in the laboratory, and the history of 

 only 28 exconjugants is known. 



Most of the abnormalities which have been described in the 

 metazoa are explained as arrests in development; as suppres- 

 sions of some part of the normal process of growth and differ- 

 entiation. Some of my abnormalities answer to this description; 



