158 TEIJI HOSHINO 



pathological changes accords with the authors who believe in the 

 similarity of these two kinds of hereditary ataxia in human cases. 



As to the real etiology of this disease, it has been assumed 

 that many factors may play a part, such as idiocy, epilepsy, alco- 

 holism, acute infectious diseases, and consanguinity of the par- 

 ents (Oppenheim, '00; Starr, '09), but none of these have much 

 real value. The connection cannot be made. They lack posi- 

 tive proof as etiologic factors. 



As circumstantial pedigrees show, all our cases descend from 

 an original egg (pigeon female, no. 151) produced by the weaken- 

 ing influence on a reproductively overworked normal parent (from 

 records of Dr. Oscar Riddle). Whether or how this overwork has 

 a direct influence on the central nervous system on exerts some 

 secondary effect on this system as a result of some nutritional 

 changes is a further difficult problem. Nevertheless, we feel 

 that we can deduce the very interesting fact that some disorder 

 or disturbance caused by 'reproductive overwork' was at least 

 an important etiological factor of this disease, and that the basis 

 for such a conclusion in the present case does not rest on uncer- 

 tain observations, as has often been done previously, but upon a 

 practical and experimental foundation. 



