140 Mujcular Fibres. [Book IX. 



the diameter of which was one-ninth of an inch; when 

 they appeared to be folid homogeneous cylinders, in- 

 terrupted at regular diftances by very minute lines or 

 wrinkles. Thefe wrinkles, when they were examined 

 in different points of view, might have paffed for glo- 

 bules j but upon this circumftance, as the obfervation 

 went no further, the Abbe does not infift. This un- 

 dulated appearance has alfo been obferved in nervous 

 and tendinous fibres, examined by microfcopes of high 

 magnifying powers. Dr. Monro, in his obfervations 

 on the nervous fyftem, gives it as his opinion, that 

 they are to be confidered as folds or joints, ferving 

 to accommodate the parts to the different ftates of 

 flexion and extenfion. In proof of this he finds, that 

 thofe parts which have this appearance in their re- 

 Jaxed ftate, lofe it when ftretched. 



Lewenhoeck long ago fancied that he had difcovered 

 the ultimate mufcular fibre, which he confidered as 

 being one hundred times as fmall as a hair. He af- 

 terwards, however, candidly acknowledged, that what 

 he fuppofed to be a fimple fibre, was, in fact, a bun- 

 dle of them. Notwithftanding, therefore, the rni- 

 crofcopical obfervations of the Abbe Fontana, and 

 other philofophers, we muft flill acknowledge our- 

 felves ignorant of the ftructure of the ultimate com- 

 ponent parts of rnufcular fubftance j and all we are 

 allowed to fay is, that their ftructure is fibrous. 

 Thefe minute fibres, obferved by. the Abbe Fort- 

 tana, were tied by cellular fubflance in fmall fafci- 

 culi or bundles, thefe bundles are again formed into 

 larger by the fame means, and of thefe fafciculi are 

 compofed thofe contractile maffes of flefh called 

 mufcles. 



Mufcles are generally connected at their two extre- 

 mities to bones, by means of tendons; the largeft part 



of 



