THE NATURAL HISTORY OF MARL 497 



and fragments of a mass of Chara plants collected from Cedar 

 Lake, and allowed to die slowly and to break up in water kept 

 cold and fresh by conducting a small stream from the hydrant 

 through it. The plants gradually died, broke up, and settled to 

 the bottom of the containing vessel and seemed to undergo 

 farther disintegration there from the growth of fungi, eventually 

 forming a relatively finely divided deposit which was of rather 

 dark color, when wet. A quantity of this was dried at I00°C., 

 some of the longer and larger fragments of stems were removed, 

 and the residue was weighed and subjected to the same treat- 

 ment as the marl samples. The analysis gave the following: 



Grade (i) 1.12^ 



(2) 24.43 



(3) ----- - 14.63 



(4) 8.26 



(5) ----- - 7-81 



Ui - - 33.S3 



(8) - 0.39 



(9) . . . - . 0.12 



Soluble organic matter and loss - - 9.4 1 



100.00 

 It will be seen that nearly as much fine matter was present in 

 this material as in the finest of the marls analyzed, and that the 

 finer grades of sifted material are quite as well represented as 

 in the finer marl. The material is somewhat more bulky for a 

 given weight and is perhaps slightly darker in color, but not 

 much more so than many samples of marl. 



Grade for grade it is identical in appearance and structure to 

 the marl samples, and the only possible difference that can be 

 detected is the slightly green tint and the organic matter present 

 in the plant residue. It is also noticeable that the larger pieces 

 do not show as thick an incrustation as do the larger pieces from 

 the marl samples and, of course, Schizothrix and other coarse 

 matter is not present. 



It will be seen by inspecting the analyses, that shells and 

 recognizable shell fragments are but a very insignificant part of 



