164. 



The attraction of cohesion in the parts of muscle appears to be 

 strongest in the direction of the fibres, and to be double that of the 

 contrary or transverse direction. When muscles cease to be irritable, 

 this attraction in the direction of the fibres is diminished ; but it re- 

 mains unaltered in the transverse direction. 



When muscles act more powerfully or more rapidly than is pro- 

 portionate to the strength of the sustaining parts, they do not usually 

 rupture their fleshy fibres, but generally break their tendons, or even 

 an intervening bone ; whence it is inferred, that the attraction of 

 cohesion is more active and powerful in the contracted state of the 

 muscle than during its relaxed or passive state. 



The muscular parts of different classes of animals vary materially 

 in colour and texture ; and such variations occur not unfrequently in 

 different parts of the same individual. 



Sect. 2. Of the anatomical structure of muscles, and their relations with 

 other parts of the animal body. The lecturer in this section professes 

 to give no more than a rapid sketch of the history of muscular struc- 

 ture. One example of the origin of a muscle he deduces from the 

 process of the incubated egg : but here it remains doubtful whether 

 the rudiments of the punctum saliens be part of the cicatricula or- 

 ganized by the parent, or merely a structure resulting from the first 

 process of incubation. The anatomical structure of muscular fibres, 

 he next observes, is generally complex, according as they are con- 

 nected with membrane, blood-vessels, nerves, and lymphseducts ; 

 which seem to be only appendages of convenience to the essential 

 matter of muscle. 



A muscular fibre, being carefully inspected in a powerful micro- 

 scope, is found to be a solid cylinder, the covering of which, as had 

 already been intimated in a previous part of the lecture, is a reticu- 

 lar membrane, and the contained part a pulpy substance, irregularly 

 granulated, and of scarce any cohesive power when dead. 



The arteries articulate copiously upon the reticular coat of the 

 muscular fibre ; they anastomose with corresponding veins ; but this 

 continued canal is not supposed to act in a direct manner upon the 

 matter of muscle. In what manner the capillary arteries terminating 

 in the muscular fibre may effect all the changes of increase in the 

 bulk or number of fibres, in the replenishment of exhausted mate- 

 rials, and in the repair of injuries, is as yet matter of conjecture ; 

 but these arteries, it is thought, must be secretory vessels for de- 

 positing the muscular matter, the lymphseducts serving to remove 

 the superfluous fluids and the decayed substances which are unfit for 

 use. These lymphaeducts appear to receive the fluids they contain, 

 not, as has been represented, from the projecting open ends of tubes, 

 but from the interstitial spaces formed by the reticular or cellular 

 membrane. 



The functions of nerves in the muscular system are the next object 

 of contemplation. These also, it seems, terminate in the reticular or 

 cellular membrane, the common integument, and the connecting 

 medium of all the dissimilar parts of an animal. We have to regret 



