INHERITANCE IN ABNORMALITIES 389 



divided, forming a giant race which was kept for about forty- 

 five days, and during that time bred true. Lewin ('10) obtained 

 abnormally-nucleate races of Paramecium by cutting an indi- 

 vidual through the macronucleus. The production of form abnor- 

 mahties in Paramecium by cutting and other experimental means 

 has been studied by Calkins ('11), Peebles ('12), Balbiani ('93), 

 McClendon ('09), and Jennings ('08). . They all found that such 

 experimentally produced abnormalities are mechanically handed 

 on to one daughter cell at each division for a longer or shorter 

 time. But such abnormal forms are gradually remodelled dur- 

 ing successive generations, or die, and their normal sisters show 

 no tendency to produce abnormal progeny. The teratological 

 variations that arise spontaneously in a culture multiplying 

 vegetatively have been studied extensively by Jennings ('08). 

 With one exception he found that all such forms either die 

 very soon or give rise to a race of normals. In one case he did 

 find that the abnormal individual gave rise to a race of abnor- 

 mals, the deformity being such as to prevent the daughter cells 

 from separating after division, thu-s forming what have been 

 called 'double monsters.' In all other cases the abnormality 

 was not a race character but an individual character and was 

 not inherited. During the course of a year's work at the Johns 

 Hopkins University I followed the history of several abnormal 

 forms which had arisen in the cultures of normals being carried 

 on by other workers in the laboratory. In no case did these 

 forms give rise to a race of abnormals; in one case a race of 

 normals resulted; in all other cases death occurred either before 

 any divisions had taken place or after one or two irregular divi- 

 sions. In rare cases, Jennings ('13) found, abnormalities may 

 arise in the members of split pairs; that is, in the members of 

 pairs separated before conjugation has been completed. But 

 these also never gave rise to a race of abnormals, either dying 

 very soon or becoming entirely normal. 



Teratological variations arising soon after conjugation have 

 been described in a few cases. Simpson ('01) observed four 

 daughter cells of a normal exconjugant Paramecium, three of 

 which were normal while the fourth was posteriorly split. This 



