5Q4 PHILOSOPHICAL TRANSACTIONS. [anNO J 722. 



Some persons might expect, that he should have looked for the extremities 

 of the blood-vessels; but these have no termination, as he has frequently said. 

 Besides, they become gradually so exquisitely fine, that the blood which passes 

 through them, can exhibit no red colour to our eyes; so that there is no tracing 

 them when entering into the vessels that return the blood back to the heart 

 except in living animals, where one may see the blood enter into the returning 

 vessels. Before the butcher gave him the uterus, he squeezed it between his 

 fingers, and said he could feel nothing in it; and this he had probably done 

 several times, by which means he tore off the vessels by which the foetus was 

 fastened to the uterus; which might be the occasion that, on opening the 

 uterus, the foetus with its coverings came forth so easily. 



Observations on the Callus of the Hands and Feet. By the same. N°373, p. J56. 



In September 17 IQ, Mr. Leuwenhoeck feeling an acute pain in one of his 

 feet, at the joint between the foot and the little toe, which he imagined to 

 proceed from the more than usual thickness of the callus or hard skin on that 

 part; he caused his servant, partly with his nails and partly with a penknife, to 

 take off that hard skin, and let it fall upon a blue paper. This callus was com- 

 posed of little scaly shivers, lying over each other, and the whole piece was as 

 large as a small nail of a man's hand. 



He viewed these shivers through a microscope, but could not satisfy himself, 

 because they lay so irregularly on each other. Then taking a little bit of it, he 

 laid it on a clean glass plate, steeped it in pure rain-water, and gently dividing 

 it with a piece of a quill, he was amazed to see into what a vast number of 

 particles it separated, and that with as much readiness as if they had never 

 been joined. 



Afterwards he took two or three of the said particles, several of which were 

 of the figure of a weaver's shuttle, broad in the middle and pointed at each end, 

 with a line in the middle, like those upon the uppermost or outside skin of 

 fruits, or of our bodies, but generally irregular; they were very thick in pro- 

 portion to their size; having laid two or three of the particles on a clean glass, 

 and put to them a drop of water as large as a coarse grain of sand, and divided 

 them; on viewing the divided particles through a microscope, he was asto- 

 nished at the prodigious number of exceedingly small particles that occurred to 

 the sight, and which were of the same figure as beforesaid. 



Since these observations concerning the friction or rubbing of his hands, Mr. 

 L. took n)ore notice of it, when washing and drying them, than formerly; 

 and was amazed at the numerous particles that daily separate themselves froiTj 



