IMPORTANT TYPES OF PEAT MATERIAL. 17 



ments of pond weed material, bits of sinootli and pustulate rootlets, 

 and in the coarser woody, cuticular, or other resistant components. 

 Animal derivatives, such as chitinized skeletal portions and egg 

 cases from insects, are frequent. 



The data in Table I are intended to show the marked differences 

 which may result from the presence of ether and alcohol soluble 

 substances, nitrogenous compounds, and products valued in the dis- 

 tillation of peat. 



Seasonal admixtures of clay, silt, and sand produce, as a rule, 

 thinly laminated gritty layers, with cleavage planes which often 

 contain leafy impressions, small stems, and other drifted material. 

 The variations in mineral matter constitute phases of the type when 

 the relative proportion, e. g., of iron, sand, silt, or clay, is above 40 

 per cent. 



132927°— 19— Bull. 802 3 



