8 Eugenics Record Office, Bulletin No. 3 



neuropathic subjects it is not surprising that we have found no 

 instance of such a mating in our material. 



§ 4. Theoretical Expectation. — We have seen that in our ma- 

 terial the correspondence between theoretical expectation and 

 actual findings is ver>' close. That is to say, the hypothesis ac- 

 cording to which the neuropathic make-up, as here defined, is 

 recessive to normal, in the Mendelian sense, is borne out by the 

 facts as shown in our pedigrees. 



Should larger accumulations of such data in the future give 

 similar results, we shall be able to establish the following rules 

 of theoretical expectation. 



1. Both parents being neuropathic, all children will be neu- 

 ropathic. 



2. One parent being normal, but with the neuropathic taint 

 from one parent, and the other parent being neuropathic, half the 

 children will be neuropathic and half will be normal, but capable 

 of transmitting the neuropathic make-up to their progeny. 



3. One parent being normal and of pure normal ancestry and 

 the other parent being neuropathic, all children will be normal 

 but capable of transmitting the neuropathic make-up to their 

 progeny. 



4. Both parents being normal but each with the neuropathic 

 taint from one parent, one-fourth of the children will be normal 

 and not capable of transmitting the neuropathic make-up to their 

 progeny, one-half will be normal but capable of transmitting the 

 neuropathic make-up, and the remaining one-fourth will be neu- 

 ropathic. 



5. Both parents being normal, one of pure normal ancestry 

 and the other with the neuropathic taint from one parent, all the 

 children will be normal, half of them will be capable and half in- 

 capable of transmitting the neuropathic make-up to their progeny. 



6. Both parents being normal and of pure normal ancestry, 

 all children will be normal and not capable of transmitting the 

 neuropathic make-up to their progeny. 



In concluding this report, we wish to acknowledge with grati- 

 tude our indebtedness to Dr. Charles D. Davenport, of the Car- 

 negie Institution of Washington, for his guidance, advice and 

 assistance in this work. 



