APPENDIX III. 187 



empty stomach may diffuse into the cartilage of the 

 hip-joint and into the aqueous humour of the eye. 

 In very young and very small guinea-pigs the same 

 quantity of lithium in thirty or thirty-two minutes 

 may give traces of lithium in the lens ; but in an 

 old animal in this time it will have got no further 

 than the aqueous humour. If the stomach be empty, 

 in an hour the lithium may be very evident in the 

 outer part of the lens, and very faintly in the inner 

 part ; but if the stomach be full of food, the lithium 

 does not in an hour reach the lens. Even in two 

 hours and a half, lithium may be more marked in 

 the outer than in the inner part of the lens. In 

 four hours the lithium may be in every part of the 

 lens, but less evidence of its presence will be ob- 

 tained there than from the humours of the eye. In 

 eight hours even, the centre of the lens may show 

 less than the outer part. In twenty-six hours the 

 diffusion had taken place equally through every 

 part of the lens. Even one quarter of a grain in 

 twenty ^our hours showed lithium everywhere except 

 in the lens. 



Experiment 17. To endeavour to determine the 

 different rate of absorption and excretion in young 

 and old animals, four guinea-pigs were taken ; two 

 were young, and two were old. The four, after 

 fasting for fifteen hours, were each given two grains 

 of chloride of lithium. Two of them, one young 

 and one old, were killed in six hours. 



The young animal showed lithium distinctly in 

 the outer and inner part of the lens, and also in the 

 cartilage of the hip-joint, when touched with a 



