No. 633] SHORTER ARTICLES AND DISCUSSION 



375 



be remembered that these figures for deaths comprise all cases 

 of absence. Mice killed in fights and animals escaped are 

 classed as dead. 



The numbers published in this note were collected only after 

 the epidemic had done its worst, and from our weighing records. 

 The epidemic seriously interfered with some of our planned 

 series in our breeding work on weight. 



It was planned to start a series of infection-experiments with 

 the isolated staphylococcus strains on families of F 2 animals. It 

 may be possible at some future date to do this, when the mate- 

 rial will again be in the right condition for the experiment, 

 that is to say, free of spontaneous infection. At present, how- 

 ever, it is evident that the staphylococcus infection is still in 

 our mousery. The mortality in F, families remains high. It 

 is clear that, if we subjected F 2 animals to infection with a pure 

 culture of the staphylococcus, the group of animals would be 

 already a selected group, and the results would be quite mis- 

 leading. 



"We have refrained from publishing these data for some time, 

 hoping that we could free our mousery from the infection, so 

 that we could repeat under conditions of a laboratory experi- 

 ment the immunity tests of F 2 families. There seems no further 

 reason now to withhold the facts such as they are. 



As far as we arc aware no wholly comparable instance is 

 known so far of a gene whose action has such a definite effect 

 upon the resistance to a bacterial disease in animals. The evi- 

 dence for the inheritance of a differential susceptibility to trans- 

 planted tumors in Japanese and large mice in the work of 

 Tyzzer is scarcely as definite as our case. 



In any case, this instance recorded here proves clearly that 

 the presence of a definite pathogenic organism as a factor in a 

 transmittable disease need not be the sole determining cause of 

 the disease. And it shows that the search for heritable factors 

 in the causation of bacterial diseases is neither hopeless nor 

 unscientific. We can only hope that cases such as the one just 

 given will encourage those medical investigators who believe 

 that predisposition is a factor not to be lost sight of in the 

 press of bacteriological and related discoveries. 



A. C. Hagedoorn-LaBrand, 

 A. L. Hagedoorn 



Berkeley, Cal., 



August 20, 1919 



