140 Of the Mufcular Fibres of Animals, 
Mr. Leeuwenhoek fays, each Mufcular 
Fibre is compofed of many fmaller Filaments 
or Fibrils ; which, however minute, he could 
plainly diftinguifh to be vafcular : for, if he 
cut acrofs their Length, the Light appeared 
through the Mouths of the Velfels; but if 
he cut them ever fo little obliquely, no Light 
was to be feen He found alfo, that each 
Fibril is inverted with a -f* minute Mem¬ 
brane, which is only a Congeries of Blood- 
Veffels, conveying Juices and Nourifhment 
thereto, though their Finenefs renders them 
Invifible. It is -not, however, to be imagin¬ 
ed, that each Fibril has its peculiar Mem¬ 
brane : but that all the Membranes together 
are like a Net finely fpread, with a Fibril 
iffuing through each of its Mefhes. 
This Structure of the Fibres he obferved 
in the Flerti of an Ox and of a Whale; but 
more plainly in that of a Whale, the Beef- 
Fibres lying more compact and clofe. He 
alfo found that the Fibres of a Moufe were 
of the fame Thicknefs as thofe of an Ox, 
though thirty thoufand Mice are not equal 
to one Ox in Bignefs : whence he con¬ 
cludes, that the different Size of Animals is 
entirely owing to the greater or lefs Number 
and Length of the Fibres 
# Pbilofopb . 'Tranf. Numb, 367, 
■f Gorter. Medic . Comp end. p. 58, 59. Leeu.w. Are * 
Nat, Tom. III. p. 58. % Ibid. p. 61 • 
Thefe 
