FUNCTIONS OF LIME SALTS. 43 



and grasses, and even some species of the Solanaceae and Lildoceae, are 

 free from calcium oxalate, they all nevertheless require lime. 



Neither Schimper nor Groom have raised the question as to why 

 oxalates, even if neutral, exert a poisonous action on chlorophyll- 

 bearing plants, while to the writer this question appeared to be the 

 most important in this connection. 



The greater lime content of the green parts first led the writer to 

 suppose that the chlorophyll bodies might contain calcium compounds, 

 and on the basis of this hypothesis he inaugurated a series of investi- 

 gations. Among other things, these showed that the neutral oxalates 

 are not poisonous to the lower fungi and that the development of these 

 is not at all retarded by adding considerable quantities of neutral 

 potassium oxalate to the culture solutions. Beer yeast is not injured 

 by adding even as much as 4 per cent of this salt to a fermenting mix- 

 ture. As in such cases the lime would become insoluble and its assim- 

 ilation would thus be frustrated, the writer has come to the conclusion 

 that these organisms do not require lime." It is otherwise in the case 

 of the higher alga?, however. As the chlorophyll bodies of Spirogyra 

 possess a highly differentiated structure, and even slight evil effects 

 readily manifest themselves in certain changes along their margin, in 

 the retraction of the lobes, etc., vacuolation of the chloroplasts, tin's 

 alga was selected for the test. When Spirogyra majuscula was put into 

 a 2 per cent solution of neutral potassium oxalate, a very striking fact 

 was brought out, many of the chlorophyll bands being injured in even 

 as short a time as thirty to forty minutes, while in even less time the 

 nucleus showed a remarkable contraction, dwindling to a mere thread 

 and thus causing a constriction of the cj'toplasm where the plasma 

 strings were attached. Moreover, filaments of Spirogyra which had 

 been exposed for ten minutes to the action of this oxalate solution and 

 had still preserved their full turgor, were incapable of repairing the 

 injury done even after being replaced in well water rich in lime, and 

 they died after twenty-four hours. Even five minutes' action ultimately 

 caused death. In a weaker solution (0.5 per cent) of oxalate the 

 nucleus does not shrink to a thread, but slowly swells up and finally 

 becomes an irregular, scalloped figure. In a still higher dilution (0.1 

 per cent) the poisonous action proceeds so slowly that it requires a 

 number of days to completely kill all the cells. 



In other species of algse, such as Vaucheria, Mbugeotia, Zygnema, 

 Cosmarium, (Edogonium, Chladophora, Sphseroplea, etc. , death, accom- 

 panied by swelling of the chlorophyll bodies, occurred after twenty- 

 four hours 1 action of a solution of 0.5 per cent. Diatoms died in this 

 solution in fifteen hours, but in a solution of 0.05 per cent some 

 diatoms were still alive after three days. In higher dilutions the pol- 

 os Erroneous representations and unjust remarks in regard to this poinl have been 

 refuted by the writer in Bot. Centralbl., 1898, Vol. LXXIV. 



