W. J. CROZIER 583 



At the same time, it seemed from my estimations highly probable 

 that the reaction of the sap from different healthy cells was not 

 always the same, even with careful precautions in taking the readings. 

 No correlation could be seen between the size of a cell and the reac- 

 tion of its fluid contents — the sap from young, actively growing 

 cells was not more alkaline than that from much larger, healthy 

 cells. 



It was shown by Wodehouse (1917) that sap from dead Valonia 

 cells contained SO4, while that from healthy cells did not; occa- 

 sional cells, otherwise healthy in appearance, showed a trace of SO4 

 when tested with BaCls. In many instances I found an acidity of 

 pH = 7.0 or less (7.0 to 8.0), always accompanied by the presence of 

 SO4. Cells obviously disorganized, though only to a slight degree, 

 were always in this category. During 3 years several hundred cells in 

 all were tested. As in some other plant cells (Haas, 1916), the 

 acidity of the vacuole content decreases as natural death approaches; 

 the reverse occurs in at least some plant cells, and in an animal, 

 Chromodoris (Crozier, 1918 h). In Valonia it has been clear that 

 natural death of a cell consumes some time; the change in the acidity 

 of the cell-sap, paralleled by the change in permeability to SO4, 

 being a gradual process (cf. Osterhout, 1917). 



BIBLIOGRAPHY. 



Chambers, R., Jr., 1917, Microdissection studies. I, Am. J. Physiol., xliii, 1. 



Crozier, W. J., 1918 a. On indicators in animal tissues, /. Biol. Chem., xxxv, 455; 

 1918 b, Fischer's theory of water absorption in edema, /. Am. Chem. Soc, 

 xl, 1611; 1918 c, On the pigmentation of a clypeastroid, Mellita sesquiper- 

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Haas, A. R., 1916, The acidity of plant cells as shown by natural indicators, /. 

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McClendon, J. F., 1918, On changes in the sea and their relation to organisms, 

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Moore, B., Prideaux, E. B. R., and Herdman, G. A., 1914, Studies of certain 

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Osterhout, W. J. V., 1917, The dynamics of the process of death, /. Biol. Chem., 

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Osterhout, W. J. V., and Haas, A. R. C, 1918, A simple method of measuring 

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Wodehouse, R. P., 1917, Direct determinations of permeabiHty, /. Biol. Chem., 

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