INHERITANCE IN ABNORMALITIES 411 



certainly the individuals that never divided, the double and the 

 monster forms, and those abnormal races in which the division 

 rate is very much lowered, can be explained in that way. But 

 in a few of the abnormal races the division rate was normal, and 

 there was very little tendency to die out; indeed they showed 

 no abnormal characters at all except the development of a 

 sUghtly bizarre form. Race C is a good example of such a race. 

 It Uved for ,191 days, had an average division rate of 1.16 per 

 day, and was consistently abnormal throughout its history. 



The mortality of the majority of the abnormal races was 

 however considerably greater than that of the normal races. 

 As the latter were all discontinued within a few days after conju- 

 gation, nine days being the usual length of time they were kept, 

 no exact comparison can be made between their mortaUty and 

 that of the abnormal races. However, they may be compared 

 in a few ways, that show there are differences between them in 

 vitality and tendency to die out. In each of the three experi- 

 ments a large proportion of the abnormal races died within two 

 weeks after conjugation, only a few races being kept for any 

 length of time. In Experiment 1 there were 21 abnormal races; 

 14 per cent (3) of these lived for over a hundred days (105, 131, 

 191) ; 29 per cent were lost or discontinued after, on the average, 

 9 daj^s of life; 12 (57 per cent) died after an average length of 

 life of 15 days, and an average number of generations, 6. This 

 gives an average division rate of 0.4 a day. The normals, dis- 

 continued 9 days after conjugation, had an average division 

 rate of 1.12 a day. The facts in the other experiments are very 

 similar to these; it is evident in all three that the abnormal races 

 have, as a rule, a lower vitality and a greater degree of mor- 

 tality. I explain this as largely due to the fact that the abnor- 

 mal forms are hindered in their locomotion by their abnormal 

 shape and so have not the normal facilities for meeting the 

 exigencies of their existence. They often lie motionless on the 

 bottom of the dish or slide for long periods; it was this lack of 

 energetic movement which made possible camera lucida draw- 

 ings of so large a proportion of them. It is probably for this 

 reason that so few abnormals are found in the usual culture. 



