ON MUSCt'LAR MjOTIOBT, JjJH 



of cherry laurel l^ivfiii employed: in each experiment* the 

 irritable limb fuftained a weight one-fixth heavier than the 

 dead limb. 



It may be remarked, in confirmation of thefe experiments. The fame do6- 

 liiat wheninufcles a6l more powerfully) or more rapidly, Uian J,""^^!^"^"^^? 

 h equal to the ftrength of the fuftaining parts, they do not living fubjeai 

 *ifually rupture their fleQvy fibres^ but break their tendons, or 

 even an intervening bone, as in the inftances of ruptured tendo 

 achillis, and frudured patella. Infiances baive hov^ever oc- 

 curred, wherein the fte^y bellies of raufcles have been 

 lacerated by fpafmodic afiions; as in tetanus the re(5li abdo- 

 minis have been torn afunder, and the gaslrocnemii in cramps ; 

 .but in thofe examples k feems that either the anlagonifls pro- 

 duce the etfed, or the over-excited parts tear the lefs excited 

 in the fame mufcle. From whence it may be inferred, that the 

 attraftion of cohefion in the matter of mufcle is confiderably 

 greater during the adt of contrading, than during the pafli\'e 

 fiale of tone, or irritable quiefcencej a fact which has hQen 

 always aflumed by anatomifts from the determinate forces 

 which mufcles exert. 



The mufcalar parts of different clafTes of animals vary in Differences 



colour and texture, and not unfrequently thofe variations occur o^^erv.eable in 

 . ^1 r • V • I 1 the colour, tex» 



m the lame individual. . ture^&c. of 



The mufcles of fifties and vermes are often coloudefs, »nufcular parts, 

 thofe of the mammalia and birds being always red ; the an*- 

 phibia, the acclpenfer, and fqualus geiiera, have frequenlly 

 both red and colourlefs mufcles in the fame animal. 



Some birds, as the black game+, have the external pectoral 

 mufcles of a deep red colour, whilft the internal are pale. 



In texture, the fafcicoli vary in thicknefs, and the reticular 

 membrane is in fome parts coarfe, and in others delicate: the 

 -heart is always compacted together by a delicate reticular 

 membrane, and the external glut:ei by a coarfer fpecies. 



An example of the 'origin o^'.nufcle is prefented in the Origfnof mufde 



.hiftory of the incubated eee, but whether the rudiments 611?^"^^^^^;,. * 

 at ^ r 1- I r I • • . •/•.., Punaum fallens 



the panctum laliens be part of the cicatncula organiled by the 



parent, or a ftru^lure relulting from the firfi procefs of incu- 

 bation, may be doubtful : the little evidence to be obtained on 

 this point feems in favour of the former opinion ; a regular 



Diftillcd oil from the leaves of the Prunus Laurccerajfvs, 

 t Ir^traotetrix, Lin# 



co;ifirm»iion 

 4 



