CXXXIT BOWMAN LECTURE. 



I have fourteen pedigrees of nystagmus not recorded 

 fully enough .to allow of their being assigned with certainty 

 to either of the two classes we have just considered, or to 

 any other recognised disease, although several of them 

 are very extensive. Eleven of them are published, the 

 latest being the one by Dr. W. H. Dudley.* Though 

 these pedigrees are inconclusive as to the nature of the 

 disease and probably in some cases not quite accurate in 

 details, they are readily divisible to sub-groups, showing : 

 (1) Continuous descent, seven pedigrees containing about 

 50 cases of nystagmus with defective sight, one of the 



pedigrees alone containing 25 cases ; in two of these 

 there was consanguinity, in the remaining five it was not 

 mentioned. (2) Discontinuous descent; four pedigrees 

 with more than 20 cases, only 4 being females ; descent 

 proved to be through unaffected mother in several 

 instances ; apparently no consanguinity in any. Mr. 

 Ernest Clarke's case belongs to this little group, but is 

 so extraordinary that I have counted it separately ; this 

 pedigree shows 22 males affected out of 23, and every 

 one of the 20 females escaping; Mr. Clarke has been 

 unable to see the recorder again in order to verify the 

 particulars. (3) In three pedigrees the descent was 

 * Dudley, W. H., A. of O., 1908. 



