No. 631] CONGENITAL PALSY IN GUINEA-PIGS 131 



until it should be able to nurse. The effort was, however, 

 unavailing, the subject gradually becoming weaker and 

 the symptoms more pronounced, until death ensued in a 

 few days. A second litter was produced by this pair on 

 May 19, 1914. This consisted of three young, which ap- 

 peared in all respects normal. On August 27, however, 

 another litter of two was produced and one of these was 

 like the abnormal individual described above. This gave 

 rise to the suspicion that the defect might he due to some 

 hereditary cause and consequently the mating of the same 

 parents was continued, with the following results: No- 

 vember 6, 1914, one defective offspring; March 24, 1915, 

 three offspring, 2 being normal and one born dead ; and 

 June 20, 1915, 2 normal, 1 defective and 1 born dead. Not 

 counting the two born dead, since their condition with 

 respect to normal reactions could not be determined, this 

 pair then produced a total of 13 young, of which 9 were 

 normal and 4 defective. These results not only strength- 

 ened the presumption that we had to deal with a heritable 

 condition, but were so close to a three-to-one ratio as to 

 suggest that' it might be a simple Mendelian recessive. 

 It may be stated at this point that further extensive ex- 

 periments have proven conclusively the correctness of 

 both of these presumptions. 



Full discussion of the symptoms and of related condi- 

 tions in man and other animals will be reserved until the 

 experimental results have been presented. It is sufficient 

 to say here that the defective condition is always clearly 

 marked and easily recognizable, and that in no case have 

 there been doubtful intermediates. Furthermore, such 

 efforts as have been made as yet to rear the defective off- 

 spring have been uniformly unsuccessful; these individ- 

 uals always die within a short time, usually within two 

 weeks of birth. 



Origin of Palsied Stock 

 Later in 1915 palsied offspring were produced by other 

 parents and studies of the pedigrees have shown that 

 such individuals have appeared in three distinct lines 



