22 
On the late Mr. Hunter's preparation 
humour a structure which corresponded with the idea he had 
formed of its actions in the human eye. He found it composed 
of laminae, whose appearance was evidently fibrous, for some 
depth from the external surface ; but becoming less and less 
distinct, till at last this fibrous appearance was entirely lost, 
and the middle, or central part of the humour, was compact 
and transparent, without any visible laminae. From this struc- 
ture it would appear, that in the eye of the cuttle-fish the ex- 
terior parts of the humour are fibrous, the interior parts not ; 
so that the central part is a nucleus round which the fibrous 
coverings are placed. The preparations which demonstrate 
these facts will be laid before the Society. 
As the structure of the crystalline humour in the cuttle- 
fish differs in nothing from that of the same humour in other 
animals, but in the distinctness of the fibrous appearance, Mr. 
Hunter was led to consider that the exterior part in all of 
them was similar, although no appearance of fibres could be 
demonstrated. 
What I have here explained, I was acquainted with at the 
time I had the honour of giving the Croonian lecture, in 
which I examined the different structures endowed with mus- 
cular action ; and was desirous that Mr. Hunter would, 
either of himself, or through me, communicate these observa- 
tions to the Society ; but this he declined doing till he had 
ascertained, by experiment, whether any muscular effect was 
really produced; and the hope of being assisted by Mr. 
Ramsden made him, from time to time, put off making his 
experiments. 
In the course of this season he began his experiments, which 
were founded upon the analogy that ought to exist between 
