344 PHILOSOPHICAL TRANSACTIONS. [aNNO 1794. 



Some time after this, having occasion to dissect the eye of the cuttle-fish, 

 which he had frequently done before, but not with exactly the same view, he dis- 

 covered in the crystalline humour a structure which corresponded with the idea 

 he had formed of its actions in the human eye. He found it composed of la- 

 minae, whose appearance was evidently fibrous, for some depth from the externa 

 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 structure it would 

 appear, that in the eye of the cuttle-fish the exterior 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. H. was led to consider that the exterior part in all of 

 them was similar, though 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 struc- 

 tures endowed with muscular action; and was desirous that Mr. H. would, 

 either of himself, or through me, communicate these observations to the so- 

 ciety; 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 oif making his experiments. 



In the course of this season he began his experiments, which were founded on 

 the analogy that ought to exist between this humour, if muscular, and others 

 of a similar structure, which led him to expect that they would be acted on by 

 the same stimuli: and having found that a certain degree of heat, applied through 

 the medium of water, will excite muscular action, after almost every other sti- 

 mulus had failed, it was proposed 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 on (he 

 humour woulil be readily ascertained. These were the experiments which Mr, 

 H. had instituted and begun; but in which he had not made sufficient progress 

 to enable him to draw any conclusions. 



To air Jos. Banks, from Mr. Hunler. 



Sir, — When I did myself the honour of giving in my claim to the discovery 



