268 THE PROPERTIES OF PROTOPLASM 



corpuscles readily. Among the alcohols there is an interesting relation- 

 ship between the number of hydroxyl-groups which they c6ntain and 

 the readiness with which they penetrate the corpuscles. The hexa- 

 tomic and pentatomic alcohols hardly penetrate the corpuscles at all. 

 Erythritol, which is a tetra-atomic alcohol arid Glycerol which is tria- 

 tomic penetrate slowly. Ethylene Glycol, which is a diatomic alcohol, 

 penetrates the cells rather rapidly, while the Monatomic Alchols divide 

 themselves immediately in equal proportion between the corpuscles 

 and the serum. Ether, esters, aldehyde and acetone, on the other 

 hand, are preferentially absorbed by the corpuscles, so that they 

 become more concentrated in the corpuscles than in the serum which 

 bathes them. Of course only those substances which fail to enter the 

 cells quickly can cause shrinkage of the corpuscles in hypertonic 

 solutions. 



THE COMPOSITION OF THE MINERAL CONSTITUENTS OF 

 TISSUE FLUIDS. 



It was first pointed out by Ringer in 1882 that the relative propor- 

 tions of the mineral constituents in the blood-sera of different mam- 

 mals are most remarkably constant and, furthermore, that notwith- 

 standing the fact that potassium and calcium salts are present in blood- 

 serum only in minute proportion relatively to the sodium salts, yet 

 their presence in the established proportion is actually essential to the 

 proper performance of their functions by the tissues, a very slight 

 alteration in the mineral composition of the fluid bathing them being 

 very deleterious. 



On the basis of numerous analyses of the ash of blood-sera, the 

 following .composition was established by Locke as the most suitable 

 circulating fluid for mammalian tissues: NaCl, 0.9 per cent.; KC1, 

 0.042 per cent.; CaCl 2 , 0.024 per cent. To this mixture a small propor- 

 tion (0.01 to 0.03 per cent.) of sodium bicarbonate is generally added to 

 neutralize the acids which are produced by tissue-activities and a little 

 glucose (0.1 per cent.) has been shown to prolong the life of excised 

 tissues which are kept for prolonged periods in this artificial circulating 

 fluid. The glucose is consumed by the tissue and probably serves as a 

 nutrient. When the glucose is omitted this mixture is usually desig- 

 nated Ringer's Solution. 



For amphibian tissues a slightly more dilute solution is employed. 

 The solution originally recommended by Ringer was a 0.6 per cent, 

 solution of sodium chloride saturated with calcium phosphate to which 

 0.03 per cent, of potassium chloride was added. A suitable fluid may 

 also be prepared by simply adding to Locke's Solution one-third of its 

 volume of distilled water. Loeb has pointed out that the proportions 

 of the various salts in Ringer's and Locke's solutions correspond 

 approximately to the ratios: 100 molecules of NaCl to 2 molecules 



