234 A STUDY OF HEREDITY IN INSANITY [Oct. 



Thus in families of patients suffering from manic-depressive 

 insanity we find not only subjects clearly recognized as insane, 

 but also subjects described as follows: high-strung, excitable; 

 dictatorial, abnormally selfish ; awful temper ; periodic drinker, a 

 demon when drunk; committed suicide; had severe blue spells. 



In the pedigrees of cases of dementia prsecox we find ancestors 

 and collateral relatives described in the following significant 

 terms : cranky, stubborn ; worries over nothing ; religious crank ; 

 nervous, queer ; restless, has phobias ; suspicious of friends and 

 relatives. 



And in the families of epileptics we find, besides cases of actual 

 epilepsy or convulsions in infancy, also cases of hemicrania, re- 

 current sick headaches, fainting spells, nervous fidgety make-up, 

 and the like. 



The limits of the legitimate extension of the conception of 

 equivalents thus seem to be beyond even the widest limits estab- 

 lished by clinical definition. 



It is not to be assumed, however, that members of the same 

 family necessarily suffer from the same neuropathic defect in the 

 shape of various clinical equivalents, for even brothers and sisters, 

 children of the same parents, may suffer from neuropathic de- 

 fects representing not equivalents but different degrees of re- 

 cessiveness. Theoretically there is, in fact, only one combination 

 of mates of which all neuropathic offspring will necessarily suffer 

 from equivalent defects. The third, fifth, and sixth combinations 

 (RRxDD, DRxDD, and DDxDD) need not be considered at 

 all in this connection as from them no neuropathic offspring will 

 result. But let us consider the remaining three combinations 

 (RRxRR, RRxDR, DRxDR) from which neuropathic off- 

 spring may result. 



If it is true that neuropathic defects may represent different 

 degrees of recessiveness, as we have endeavored to show in a 

 preceding section, then in the case of any neuropathic subject we 

 have no way of telling whether the inheritance of his defect is 

 homozygous or heterozygous, unless we possess an exceptionally 

 detailed pedigree extending far back to past generations ; in other 

 words, we cannot tell whether he inherits from the two parents 

 defects of the same or of different degrees of recessiveness. Con- 

 tinuing to make use of the symbols R and r to represent, re- 



