572 



Howard : Tannin cells of persimmons 



figure 6. There is no definite portion of the cell- wall where rup- 

 ture occurs ; sometimes this happens at one end and at other times 

 at some point along the side of the cell. The form of energy pro- 

 ducing the bursting is undoubtedly osmotic pressure, for solutions 

 of fairly strong osmotic power cause no increase in size or bursting 

 when pulp cells are mounted in them. In order to demonstrate 

 this we used glycerine solutions as well as aqueous solutions of 



Figure 5- Japanese persimmon tannin cells (masses), showing small vacuoles 

 on surface. X 2 5- 



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sodium chloride, potassium bromide, potassium iodide and sodium 

 sulphite. Even the tannin reaction with fairly strong iron chloride 

 solution proceeds with exceeding slowness where rupture of some 

 kind has not occurred. It appears that if the iron chloride solu- 

 tion is about isotonic with the solution within the cell, sufficient 

 water cannot pass in to produce rupturing and thus bring the cell- 

 contents in contact with the reagent ; and furthermore that the iron 

 salts are prevented, except in comparatively few instances, from 

 passing into the cells and producing the color reaction there. 



