THE NATURAL HISTORY OF MARL 505 



small per cent., and is concentrated in the cells of the plant as 

 calcium succinate and later deposited upon the outside of the 

 same cells as the normal or monocarbonate in crystalline form 

 in considerable quantities. 



Some culture experiments which were undertaken by the 

 writer to determine under what conditions of soil, light, and 

 temperature Chara thrives best, incidentally demonstrated that 

 the plant actually gets its lime from the water and not from the 

 soil. One of the soils which was used as a substratum in which 

 to grow plants was pure quartz sea-sand which had been washed 

 with acid to remove any traces of calcium salt which might be 

 present. The plants grew in this medium readily, and on the 

 newer parts developed nearly, if not quite, as many calcium 

 carbonate crystals as plants growing in pure marl. It should be 

 apparent, however, to even the casual observer that the plants 

 cannot take all the lime they precipitate from the soil, or even a 

 considerable part of it, for if they did the marl beds, being made 

 up principally of Chara remains, would never have accumulated, 

 for the material would have been used over and over again and 

 could not increase much in amount, if it increased at all. In 

 the present state of our knowledge of the life processes of 

 aquatic plants, it seems hardly possible to state the probable 

 method of the formation of the calcium succinate, or even the 

 probable use of it to the plant, and no attempt will be made by 

 the writer in the present paper to do so. It does seem probable, 

 however, that this compound accumulates in the cells, until it 

 reaches sufificient density to begin to diffuse through the cell 

 walls by osmosis. Outside the cells, or in its passage through 

 the walls, it is decomposed directly into the carbonate, possibly 

 by oxidation of the succinic acid by free oxygen given off by 

 the plants, possibly by some substance in the cell walls, or, 

 more probably, by the decomposition of the acid by some of 

 the organic compounds in the water, such as the organic fer- 

 ments, due to bacterial growth in the organic debris at the 

 bottom of the mass of growing Chara. The water extract of 

 Chara rapidl}^ changes on standing, undergoing putrefactive 



