No. 631] CONGENITAL PALSY IN GUINEA-PIGS 149 



sible in animals where breeding experiments can be con- 

 ducted, to use the inheritance method for separating nerv- 

 ous diseases in which the symptoms are so similar as to 

 be confusing, or even identical. For example, let us sup- 

 pose that a recessive neurosis similar to congenital palsy 

 should appear in another line of guinea-pigs. If animals 

 heterozygous for it were mated to heterozygous individ- 

 uals of our stock and they produced affected offspring in 

 a one-to-three ratio, it would be good evidence that we 

 were dealing with the same heritable trait in both strains. 

 If, however, the disease in the new line was genetically 

 different, a different ratio of offspring would be expected, 

 presumably nine normal to seven neurotic individuals, 

 assuming that there was no linkage of the two genes con- 

 cerned. It is possible that even in man when the family 

 histories are sufficiently complete the method of genetic 

 analysis may help in the differentiation of neuroses char- 

 acterized by symptoms which are confusingly similar. 



Summary 



1. A definite neurosis appeared in our guinea-pig stock 

 in 1914, characterized by clonic spasms, particularly of 

 the legs. "When in a spasm the animals lie on their sides 

 in a helpless condition. This state is induced by various 

 stimuli, but especially by those of a sharp auditory 

 nature, and also by attempted volitional movements of 

 the legs. 



2. The affected animals are fully up to average weight 

 when born, and appear to be normal in all other respects. 

 While different individuals vary with respect to the in- 

 tensity of the symptoms at birth, they are always easily 

 distinguished from normal young, and in all cases the 

 disease runs a short progressive course, terminating in 

 death within about two weeks at most. 



3. This defect, which we have called congenital palsy, 

 is definitely heritable. It is a simple Mendelian recessive, 

 and normal and affected offspring are produced by two 



