VITAL PROPERTIES OF MUSCLE. 7 



by Professor Harting,* who observes that the average diameter of the 

 fibres in the new-born child is to that in the adult as 1:3*64, and that 

 the respective average intervals between the transverse striae are as 

 1:1'18. He finds, also, that in the child the distance between the 

 strise is to the width of the fibre as 1:4'415 ; in the adult as l-:8'42. 



Attachment of muscle to tendon. Mr. Pagetf has recently discovered a 

 new mode of attachment of the ultimate fibres of muscle to their tendons : 

 it was observed in the muscle torn out from the leg of a fly. " Each of 

 three tendons, which are planted in the proximal end of the last but one 

 articulation of the leg, runs in a long, straight, and flat band up the in- 

 terior of the next superior division of the limb, and receives on each of 

 its edges the broad and somewhat rounded bases of the muscular fibres. 

 These are arranged in a penniform manner, the base of each fibre on one 

 side of the tendon corresponding to the halves of the bases of two adja- 

 cent fibres on the opposite side, like the leaflets of the Pteris and some 

 other ferns. The fibres are flat, and their extremities, instead of being 

 ensheathed in the tendinous tissue, only adhere to the border of the tendon, 

 and receive on their outer edges one or two finer tendinous filaments, as if 

 for greater fixity." 



Involuntary muscles which are composed of striped fibres. In addition 

 to the heart, which is the only involuntary muscular organ mentioned 

 by Professor Miiller,$ as having the striped or beaded variety of mus- 

 cular fibre in its composition, must now be enumerated the lymphatic 

 hearts of reptiles and birds ; the coats of the stomach arid intestines of 

 the tench, and of the stomach in the common roach. || 



Of the vital properties of muscle. 



The apparent hardness of muscles in the state of contraction has been 

 shewn by Professor Ed. Weber IF to be caused by the tension which their 

 fibres, as well as their tendons and other tissues, are subjected to from the 

 resistance ordinarily opposed to their contraction. For, when no resistance 

 is offered, as when a muscle is cut off from its tendon, no hardness is per- 

 ceptible during contraction ; indeed, he finds that the muscular tissue is 

 then even softer, more extensile, and less elastic than in its uncon- 

 tracted state. 



Changes in muscle during its contraction. From what has been learned 

 of late concerning the minute anatomy of striped muscular fibre, and from 



* Tijdschr. Voor Natur. Geschied. en Physiol. d. xii. quoted in Mr. Paget's Report on 

 Physiology in 1 844-5, p. 1 1 . 



t Report on Anatomy and Physiology for 1842-3, p. 6. 



Physiology, p. 879. Prof. Stannius in Muller's Archiv. 1843. 



II Prof. Budge, Schmidt's Jahrb. 4, 1847. 



H Loc. Cit. Art. Muskelbewegung, p. 54. 



