No. 590] 



TRANSMISSION OF DEGENEEACY 



79 



When such F x animals are paired with normal indi- 

 viduals the seventh line shows that almost 22 per cent, 

 of the matings failed, which is not a bad record. The 

 proportion of stillborn litters, however, from the F x by 

 normal combination was three times as great as from 

 normal matings and 75 per cent, of the stillborn young 

 produced showed gross defects of the eyes, having opaque 

 lenses or typical cataract conditions, while not one of 126 

 young from normal matings has shown this or any other 

 noticeably abnormal structure. Thirty-three living lit- 

 ters were produced containing in all 54 individuals, 29, 

 or 54 per cent., of which died soon after birth, while 25 

 survived. Two of those dying soon after birth were par- 

 alyzed and unable to walk, while three of the 25 survivors 

 have defective opaque eyes, cases similar to that illus- 

 trated by Fig. 1, and many show different nervous symp- 

 toms. Thus of 62 full-term young produced by F l ani- 

 mals with normal mates, only 25, or 40 per cent., survived 

 for more than a short time after birth, and 12 per cent, 

 of these have gross defects and more than half of them 

 are nervous, excitable individuals, which when mated with 

 normal animals or in any other combination always give 

 very poor quality offspring, if any at all. 



The eighth line shows the records of 53 matings be- 

 tween F x animals and alcoholics. This combination again 

 gives data comparing most unfavorably with the control 

 and in some ways even worse than the records of matings 

 between two alcoholic animals. Fifteen per cent, of such 

 matings produced stillborn litters! Only one combina- 

 tion gives a worse record of stillborn that is, matings 

 among F 2 animals. Almost half of the young in the liv- 

 ing litters died and here again some were deformed. De- 

 formities are strikingly more abundant among the off- 

 spring from F t and F, parents than from the directly 

 alcoholized animals. 



The record of 95 inter se matings of F x animals is 

 shown in the ninth line. Thirty per cent, of such mat- 

 ln gs gave negative results or early abortions, over 7 per 



