840 OF THE STRUCTURE AND FUNCTIONS OF MUSCULAR TISSUE. 



7700 grammes for the square centimetre. Mr. H. F. Baxter 1 found from 

 his experiments that 1 grain of frog's muscle is on the average capable of 

 raising a weight of 608 grains through a space of g'gd of an inch, though 

 considerable differences exist in regard to sex, age, and general condition 

 of the animal. Thus he found that whilst 1 grain of the muscle of male 

 frogs could raise 656 grains, 1 grain of the muscle of female frogs could only 

 raise 579 grains. Again, in March and April 1 grain of frog's muscle 

 raised 445 grains -g-^d of an inch high, in June and July 608 grains. 2 

 This agrees with the observation of Schmulewitsch, 3 that within certain 

 limits the higher the temperature of muscle, the more work is it able to 

 perform with equal weighting and stimulus. Fick 4 finds the power pos- 

 sessed by 1 grain of frog's muscle to be 5000 millimetre-grammes for one 

 single contraction. Haughton 5 estimates that one ounce of the human 

 heart will lift 20.576 Ibs. through a height of one foot per minute, and 

 that 1 Ib. av. weight of human muscle is capable of lifting 1.56 ton 

 through 1 foot before it is exhausted. Mr. Baxter's experiments also show 

 the interesting circumstance that whilst there is a loss of weight in the 

 animal during prolonged muscular contraction, there is an increase of 

 weight in the individual muscles experimented on. It is to be recollected, 

 that the mechanical application of the power developed by muscular con- 

 traction to the movement of the body, is very commonly disadvantageous as 

 regards force : being designed to cause the part moved to pass over a much 

 greater space than that through which the muscle contracts. Thus the Tem- 

 poral muscle is attached to the lower jaw, at about one-third of the distance 

 between the coudyle and the incisors ; so that a shortening of the muscle to 

 the amount of half an inch, will draw up the front of the jaw through an 

 inch and a half; but a power of 900 Ibs. applied by the muscle, would be 

 required to raise 300 Ibs. bearing on the incisors. In the case of the fore- 

 arm and leg, the disproportion is much greater ; the points of attachment of 

 the muscles by which the knee and elbow-joints are flexed and extended, 

 being much closer to the fulcrum, in comparison with the distance of the 

 points on which the resistance bears. Professor Haughton has also shown 

 that there is a loss in the force applied by the muscles of various animals in 

 consequence of the friction of their tendons, which amounts in man to 35 

 per cent., in the mastiff to 41 per cent., and in the kangaroo to 61 per cent. 

 It may be instructive to append here the estimates made by different ob- 

 servers of the amount of work that a man weighing about 150 Ibs. can with 

 vigorous exertion accomplish in the course of a day of eight hours. The 

 French assume as a work-unit the force that is requisite to raise 1 kilo- 

 gramme (=2.2 Ibs.) 1 metre (~ 39.37 in.) high in one second of time : 



Amount of work 

 Kind of labor. in foot tons. Authority. 



Pedestrians, ..'....... 353 Haughton. 



Pile-driving, 312 Coulomb. 



Pile-driving, ......... 352 Lainumlc. 



Turning a winch, ........ 374 Coulomb. 



Porters carrying goods and returning unloaded, . . 325 u 



Porters always loaded, ....... 303 



Porters carrying wood upstairs and returning unloaded, 381 



Paviors at work, 352 Haughton. 



Prisoners at shot-drill, 310 " 



1 On Muscular Power, in the Edin New Phil. Journ., vol. xviii, p. 194. 



2 Archives of Medicine, vol. iv, pp. 298 and 32(i. 



8 Centralblatt, 18(57, No. 6; and Modicin. Jahrb., Bd. i. 



4 Yin-how's Jahresb. for 1867, p. 80. 



5 Outlines of a New Theory of Muscular Action, Dublin, 1863. 



