SPONGE SPICULES IN SWAMP SOILS. 



through whose interstices the currents meander, is composed of siliceous spicules, 

 slightly bound together by an almost invisible quantity of firm sarcode, or, parhaps, 

 of colloidal ilica. In the different species these skeleton epicules vary in size, in 

 the shape of their terminations, and in their more or less spinous character. 



The soils of the region investigated carried as high as 25 percent 

 of these spicules. Of course, their presence in such quantities is 

 unusual and presents a problem to the soil technologist. Importance 

 attaches to its solution, because any land that has remained as a 

 swamp for a long time may be infested with these spicules. Their 

 presence has been frequently noted in regular mineralogical examina- 

 tions of soils and evidently they are quite widely distributed. 



Examinations were made of nearly 200 samples of soil from dif- 

 ferent parts of the United States taken from beds of lakes and from 

 swamps. Spicules were found in nearly all, but generally in very 

 small quantities. Those in soils from other localities than Georgia 

 varied somewhat in character. They were crescent shaped but did 

 not have the small spines on their surfaces. The quantity in the 

 soils of the Klamath project of Oregon was large. Diatoms were 

 also present. The muck soil of Florida showed the spicules in the 

 greatest abundance, with the exception of the Georgia soils already 

 mentioned, but the spines were missing from them also. In none of 

 40 soils collected from the cypress swamps and bayous of Louisiana 

 and other Gulf States were the spicules found in any quantity. 



It was desired to know whether these sponge spicules were present 

 in the lower layers of soil and, if so, in what amounts. Prof. W. A. 

 Worsham, of the University of Georgia, secured samples from the 

 spot near Montezuma, Ga., showing 25 per cent of spicules. These 

 samples were carefully taken at different depths and sent to this 

 bureau. Dr. Mann made an examination of these samples to deter- 

 mine the relative number of spicules at the different depths. This 

 was done by preparing representative samples on slides and making 

 counts of the number of spicules in each sample. The result 

 follows : 



Quantity of sponge spicules in the soil at different depths. 



