23 
for the Croon ian Lecture . 
this humour, if muscular, and others of a similar structure, 
which led him to expect that they would be acted upon by the 
same stimuli : and having found that a certain degree of heat, 
applied through the medium of water, will excite muscular ac- 
tion, after almost every other stimulus had failed, it was pro- 
posed to apply this to the crystalline humour, and ascertain 
its effects. 
The crystalline humour taken from animals recently killed, 
must be considered as being 'still alive. Such humours were 
to be immersed in water of different temperatures, and placed 
in such a manner as to form the image of a lucid well defined 
object, by a proper apparatus for that purpose, so that any 
change of the place of that image from the stimulating effects 
of the warm water upon the humour would be readily ascer- 
tained. These were the experiments which Mr. Hunter had 
instituted and begun ; but in which he had not made suffi- 
cient progress to enable him to draw any conclusions. 
To Sir Joseph Banks, from Mr. Hunter. 
Sir, 
When I did myself the honour of giving in my claim to the 
discovery of the crystalline humour being muscular, and pro- 
posed to make it the subject of the Croon ian lecture, I did not 
foresee that any thing could prevent me from fulfilling my 
promise ; but since that time, what with my state of health, 
which does not allow me to be very active ; the hurry of offi- 
cial business on account of the war, and my brother-in-law, 
Mr. Home, being employed on the medical staff', I have not 
had the power of repeating my experiments, and drawing out. 
