158 PROTOPLASMIC ACTION AND NERVOUS ACTION 



Ringer's solution reflex activity may continue for days. 

 If the cord and attached sciatic nerves are immersed 

 in isotonic sugar solution, reflexes completely disappear 

 within twenty-four to thirty-six hours; on returning the 

 cord to Ringer's solution they return in a few hours. 

 In perfused frogs, replacement of the blood by sugar 

 solution rapidly causes disappearance of reflexes and 

 later of direct muscular irritability: perfusion with pure 

 NaCl solution then restores direct muscular irritability, 

 but not indirect or reflex, while Ringer's solution restores 

 all three. The quantity of Ca necessary for restoring 

 reflexes (as well as indirect irritability) is very shght. 



In the observations above most of the fundamental 

 phenomena of salt action are illustrated — the necessity of 

 salts for cellular activity, the toxic action of pure solu- 

 tions, ion-antagonisms, and especially the remarkable 

 role of calcium in maintaining the normal structural 

 and functional relationships between cells. With regard 

 to this latter phenomenon, Overton cites Herbst's 

 observations on the action of calcium in promoting the 

 coherence of blastomeres,^ and also calls attention to the 

 presence of this element in the middle lamella of plant 

 tissues, where, according to Mangin, it is present as a 

 compound, Ca-pectate (or pectinate), which is necessary 

 for intercellular coherence. When this compound is 

 removed (by weak acid) or when it is substituted by the 

 Na salt (e.g., in pure NaCl solution) the cells fall apart.^ 

 Apparently some Ca compound is necessary for the 



' Herbst, Arch. Entwicklungsmech., IX (1900), 424. 



2 Compare the recent observations of Hansteen on plant tissues; 

 again pure NaCl solutions cause a disintegration due to loss of intercellular 

 coherence: Jahrb. wiss. Botanik, XLVII (1910), 289; LIII (1914), 536. 



