524 PHILOSOPHICAL TRANSACTIONS. [aNNOJ721. 



the circumference of the fibre. In one fibre I saw at least 50 of these vessels 

 running through each other. 



On this discovery, I found I had been mistaken in what I had at first ima- 

 gined, which was, that the vessels, which arose from the membranes, proceeded 

 no farther than just through the tunicle of the fibre, and so discharged the 

 fluid into the fibre for its nourishment. Whereas now I perceived that the 

 vessels, which arose from the membrane, and entered into the fibre, did not 

 end there, but spread themselves into smaller branches, proceeding every way 

 from the inside to the tunicle of the fibre. Hence I imagined, that the nutri- 

 tious juice might circulate in these small vessels, just as the blood does in the 

 veins and arteries; and that what the muscular fibres received from them, 

 might be no more than what oozed through the tunicles of these small vessels, 

 as I have said of the small vessels in land-animals, which have no other termi- 

 nation than the artery coming from the heart, and the vein terminating in the 

 heart ; the artery and vein thus making one continued vessel. 



Yet I could not discern, in the transverse sections of the fibres, any appear- 

 ance of those vessels which run along their length, and compose the greatest 

 part of the body of each fibre. This I imputed to the cutting of those vessels 

 not directly across, but somewhat obliquely, by which their apertures had been 

 closed in such a manner, that I could not perceive the least resemblance 

 of them. 



In viewing an entire muscle of a cod-fish, and the fibres of which it was 

 composed, I found the thick end of the muscle to equal the back of an ordi- 

 nary knife, and the thinner end not to exceed the thickness of a single fibre. 

 Many of these fibres are twice as long as the thickness of the muscle, and be- 

 tween the muscles lie what are commonly called membranes, which are nothing 

 else but a congeries of vessels. These vessels do not only run between the 

 fibres, but into the very substance of every fibre, as we see, when the fibres 

 are cut transversely. By these vessels the muscular fibres, and the entire 

 muscles themselves are so firmly bound together, that they serve instead of 

 tendons to each other. In like manner the muscular fibres are united to the 

 bones, by the vessels proceeding from the bones, which vessels compose what 

 in land-animals is called the periosteum. 



Fig. 10, pi. 14, represents two muscles of a cod-fish, lying close together, 

 as they are united to each other, and separated from the other muscles; the 

 part ABC having been covered with the skin near the head of the fish: and 

 I am of opinion, that the body of the cod-fish, from head to tail, consists of 

 a continued series of such muscles. Fig. 1 1 represents a single muscle of the 

 fish : where ehg shows the thickness of the muscle; and its thin edge, which 



