coville: formation of leafmold 87 



it for like the leaves of trees many of the crops of agriculture 

 are heavy with lime and their uncompensated removal year after 

 year has its inevitable cumulative result. 



The speaker hopes that he does not overstep the proper bounds 

 of this address if he calls attention to conditions in bog deposits 

 which almost exactly parallel the two types of terrestrial organic 

 formation, leafmold and upland peat. In bogs with alkaline 

 waters, as for example those underlain by marl, a condition of 

 permanent acidity is not maintained in the lower strata of the 

 deposit. As far upward as the alkaline waters penetrate, the 

 antiseptic acids are not present, decay continues, and the result- 

 ing formation is not peat, but a plastic fine-grained black material 

 that may best, perhaps, be designated by that much misused 

 term muck. Muck corresponds in bog deposits to leafmold in 

 upland deposits, contrasting with bog peat as leafmold contrasts 

 with upland peat. 



We may follow this idea one step further. Coal is petrified 

 peat. As the purest peats are not formed in alkaline waters, 

 it can not be expected that the best coal will be found in situa- 

 tions indicative of alkaline conditions. If coal is found imme- 

 diately overlying beds of marl or limestone it is to be expected 

 that such coal will be of an impure type corresponding in origin 

 to muck. The speaker takes the liberty of suggesting to his 

 geological friends that in reconstructing in theory the climatic 

 and other conditions under which the various kinds of coal were 

 deposited they may safely hypothesize that the purer coals were 

 laid down in waters that were acid. 



Allusion has been made to the peculiar characteristics of plants 

 that inhabit peat. Among these peculiarities perhaps none is 

 more remarkable than the presence of mycorhizal fungi on the 

 roots of many, perhaps most, peat-loving plants. It is known 

 that peat is very poorly supplied with nitrogen in the form of 

 nitrates, which most plants of alkaline soils appear to require. 

 Organic nitrogen, however, is abundant in peat and there is 

 very strong evidence that these mycorhizal fungi take up this 

 organic nitrogen, and possibly atmospheric nitrogen also, and 

 transfer it in some acceptable form to the plants in whose roots 



