VOL. XXiri.3 PHILOSOPHICAL TRANSACTIONS. 3> 



and bring the other backward at the same time, and this alternately, by which 

 means they seem to grind their food. 



Having pulled off a handful of muscles, which stuck to a piece of a rock that 

 was covered by the sea every tide; I found that the organs by which they fix 

 themselves so firmly to a stone, that even a storm will not wash them off, were 

 threads which proceeded from that part called the beard of the muscle, and 

 which had on their extremity a flat spongy substance, that adhered only by im- 

 position, like the suckers or wet pieces of leather which boys fasten to stones, 

 and they are very well described and represented by M. Leuwenhoeck. I also 

 viewed and examined the inhabitants of those little white shells,* which stick 

 like pustules on muscle-shells, as also on lobsters, oysters, stones, &c. These 

 are also mentioned by M. Leuwenhoeck, who gives a picture of one of these 

 little animals, taken out of its shell, which is very accurate, only that in the J 2 

 long branches growing from the head, the bristles are there represented coming 

 out quite round on each joint of every branch ; whereas they grow only on the 

 inside, (all the hind part being perfectly bare) and look not unlike a ruffled 

 feather stripped on one side. I cannot guess at the use of these curious ramifi- 

 cations, unless they serve to draw in the food of the animal, which cannot move 

 out of its place. For keeping them alive in sea-water, I saw them often put 

 those branches out through the slit of the operculum, which closes the top of 

 the shell, and draw them in again. 



Some of the muscles which I brought were little more than a quarter of an 

 inch long. I took one of these out of the shell, and exposed it to the micro- 

 scope on a thin plate of Muscovy glass, and holding it to the light of a candle, 

 saw in the thinner parts a vast number of veins and arteries, and the blood 

 circulating in them more distinctly than I ever saw it in any other animal : for 

 I had this advantage in the observation, that the object lay always quiet, with- 

 out changing place, and my plate was so thin that I could bring to it what mag- 

 nifiers I pleased, and look without disturbance as long as I pleased ; for where- 

 as other animals will not easily be brought to lie still any considerable time, and 

 will not live long when exposed to a microscope, this lay always in the same 

 position, and the motion of the blood continued with little alteration 6 or 7 

 hours, only by keeping the object moistened with sea- water, and might have 

 lasted much longer, had I not thrown it away. I repeated the same experi- 

 ment, for '2 or 3 days, with some of the remaining muscles, with little differ- 

 ence in the success. 



Observing a small worm running among some fruit, which I could perceive 



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