C 3^2] 
the Small pocks^ and perhaps the blood may be more 
gently ftrained through thefe paflages for the nouriffiing 
of fome parts of the body. 
I examined one of the Mufcles of the hinder leg of a 
frog^ which confifted oi filaments^ and thofe again of a 
great number of leffer filaments^ but becaufe they had 
more rings in them then I had formerly feen in the mul- 
cular threds of an Oxe, Fly, Gnat^ Flea or Loufe^ I have 
here reprefented part of one in FigX, fuch numerous rings 
I havelince met with in ihe filaments thQ Alufcleof z 
Z^w^, taken from the rim of the Belly, near the hinder 
leg. From the indentings of theie filame?its I cannot on- 
ly latisfy my lelf how the limbs come-to ftand bent, when 
the mufcles are at reft, but alfo why we can walk a longer 
time then ftand ftilh- and why our ^r;wi when we walk 
do not hang down at their full length, ftretcht out by our 
fides ; but more backwards and forwards ; for if the Arms 
ftiould ftill hang ftrait down, then would onQ Mufcle hQ 
ftretcht too much, and another bent or drawn up too 
clofe; both thele things difagreeing with the Natural 
conftitution of the Mufcle^ and for this reafon it is, that 
when we ftand a long time, we do not reft equally upon 
both legs, but firft raife up one foot, then the other, touch- 
ing the ground only with the fore part of the foot, while 
the Mufcles of that leg reft themlelves. 
I have beeu puzzled why fome of the wrincles in the 
filaments of Flefli and Filh mufcles, were fetpentine, as I 
.reprefented in my letter of the id. oi March [Fig. ijL 
E E G H and I K L M.) but I confider that the filaments 
lofe their roundnels by being prefthard upon one ano- 
ther. It is alfo probable that they may be bent after that 
manner by the evaporating of their moyfture, which 
makes up | parts of their bulk : asi^^. ^.a^y^., isaFi- 
lament Mhich had been round, but is now alterd by the 
evaporating of its moyfture, and bended in as at where- 
