SALTS 



439 



accelerates diastole and thus nicely counterbalances calcium 

 without robbing it of its beneficial effects. The solution was 

 further slightly improved by the addition of a small amount of 

 sodium bicarbonate, which produces a slight alkalinity similar to 

 that existing in the blood and maintains this alkalinity (like a 

 buffer) by neutralizing the acid produced by the heart muscles 

 in contracting. Thus resulted the now justly famous Ringer's 

 solution the composition of which is as follows : 



Parts 



NaCl 6.5 



KCl 0.14 



CaCU 0.12 



Parts 



NaHCOs 0.2 



NaH2P04 0.01 



Water 1,000 



Such a solution is said to be physiologically balanced. 



Magnesium is omitted from Ringer's solution though it is put 

 in all artificial plant nutrients and occurs in sea water. The 

 following two lists give the salts found in the ocean and those 

 which make a good imitation sea water for laboratory work : 



Ocean 

 (To 1,000 parts) 



Grams 



NaCl 26.86 



KCl 0.58 



Artificial 

 (To 1,000 cc. of distilled water) 



Grams 



NaCl 30 



KCl 0.8 



MgS04 6.6 



CaCl2 1-3 



(NaHCOs as a buffer) 0.5 



MgCU 3.24 



MgS04 2.20 



CaS04 1-35 



Rest 0.07 



There is a surprisingly close agreement in the proportions of 

 the three important elements sodium, potassium, and calcium, 

 in Ringer's solution and in a number of natural solutions which 

 serve as a medium for maintaining life. How striking this is 

 is to be seen from a comparison of the quantities of these ele- 

 ments in three physiologically balanced solutions: 



It has been suggested that the salt of the blood of land verte- 

 brates is an inheritance from marine ancestors. When verte- 



