Hypothesis of Contraction of Striated Muscle. 147 



Sheep's blood was centrifugalised and the corpuscles washed once with 

 0'9-per-cent. sodium chloride. The corpuscles were diluted with an equal 

 volume of distilled water and the resulting solution of haemoglobin was placed 

 in osmometers. 



Solution outside 

 osmometers. 



Maximum pressure. 



Time, 

 in days, to 

 maximum. 



Percentage 

 of organic 

 matter. 



Pressure per 

 1-per cent, 

 of organic 

 matter. 





mm. 









600 c.o. water 



108 



2 



14 -8 



7-3 





100 



2 



14 -6 



6 -85 



600 c.c. -01 N lactic acid 



248 "1 Average in- 



8 



14 "5 



17 -2 



600 c.c. -01 N lactic acid 



266 J crease 153 



7 



14 -0 



19 -0 



This experiment illustrates how the anisotropous substance may swell 

 as the result of an increase in osmotic pressure due to the formation of 

 lactic acid. 



Bernstein (2) states that the force of frog's muscle is about 600 grin, per 

 square centimetre, which amounts to a pressure of 445 mm. of mercury. 

 The percentage of protein in muscle is about 18, so this is equivalent to 

 24 - 8 mm. per 1 per cent, of protein, a pressure not much greater than that 

 recorded above with a strength of acid which is less than that formed in 

 muscle during contraction. 



Macallurn(8) and Macdonald (12) have shown that the inorganic con- 

 stituents of muscle are mainly confined to the dim band. Some years ago 

 1 endeavoured to find out if the proteins were also mainly confined to the 

 dim band. Crab's muscle was stained by immersion in dilute Millon's 

 reagent, copper sulphate followed by alkali, and other protein reagents. 

 In each case the dim band appeared to stain more deeply. The experiments 

 were discontinued, as the appearances might have been due to the colour 

 seeming darker because of the opacity of the dim band. If the proteins are 

 unequally distributed less pressure per 1 per cent, of protein would suffice 

 for muscular contraction. 



Another way to calculate the osmotic force of muscular contraction is to 

 regard the increase of pressure as due to the amount of lactic acid combined 

 •as an ionising salt with protein, the increase in pressure being considered to 

 be due to the addition of the lactic ion to the protein. 



The increase in pressure (153 mm.) is equivalent to a - 009 normal 

 solution. This added to the - 01 normal solution, the amount of uncombined 

 acid which should be equally distributed inside and outside the osmometer, 



