THE MOVEMENTS OF ORGANISMS 291 



E. B. MEIGS* studied the rate at which fresh muscles in- 

 creased their weight in water and in salt solutions. He concluded 

 from his study that the weight increase is the result of two processes: 

 At first, water is osmotically taken up by the sarcoplasm of the fresh 

 (still irritable) muscle; after the muscle is dead, lactic acid forms, 

 the semipermeable membrane of the fibrils (the sarcolemma) becomes 

 permeable and now the fibrils swell up at the ex- 

 pense of the sarcoplasm fluid and are thus 'short- 

 ened; this is evidenced by rigor mortis (0. VON 

 FURTH and LENK). The proteins become co- 

 agulated through the accumulation of acid; this 

 especially induces a shrinking and thus a relaxa- 

 tion of rigor mortis. By this experimentally es- 

 tablished explanation 0. VON FURTH and LENK 

 have cleared away an old fallacy that the onset 

 of coagulation induced rigor mortis. By artifi- 

 cial fatigue (e.g., electrical stimulation of an FlG - 49 - Striated 

 excised frog's muscle) the accumulation of acid UCe flber * 



and the consequent swelling of muscle in dilute 

 salt solution is much hastened (C. SCHWARZ *). It is a well-known 

 fact, moreover, that after great muscular exertion (forced marches, 

 convulsions, hunted prey), rigor mortis sets in sooner than when 

 death overtakes a rested organism. 



When rigor mortis disappears striated muscle behaves like an 

 hydrophile colloid, whose swelling and shrinking are unhindered by 

 semipermeable membranes. 



A further study of E. B. MEIGS * is concerned with the nature of 

 the semipermeable membrane of a fibril. It tends to show that the 

 latter consists of calcium phosphate. Collodion membranes impreg- 

 nated with calcium phosphate proved impermeable for salts, sugar 

 and amino acids, but were somewhat permeable for glycerin and urea 

 and easily permeable for ethyl alcohol. They were moderately perme- 

 able for potassium chlorid as was to be expected. The predication of 

 a semipermeable layer of calcium phosphate explains two facts very 

 well: 1. The suspension of the semipermeability of muscle after 

 death (the accumulation of lactic acid destroys the membranes) and 

 2. the importance of calcium for the maintenance of semipermea- 

 bility in living muscle; since the layer of calcium phosphate is de- 

 stroyed in a neutral lime-free solution. 



A unique observation was made by M. H. FISCHER and P. JENSEN * 

 upon the water in muscle. They put the gastrocnemius of frogs into 

 narrow glass tubes, cooled them down to 76 in a mixture of 

 ether and solid C0 2 , and followed the curve of cooling with a needle- 



