44 The Ohio Journal of Science [Vol. XIX, No. 1, 



tance. There can be no question but that its presence greatly 

 mitigated and shortened the period of the prevalence of the 

 dust storms which afflicted the country after the eruption. 

 It provided, moreover, a protection that gave very great 

 assistance to the seedlings of other plants. Many areas now 

 support an abundance of seedlings w^hich would undoubtedly 

 still be barren wastes if it had not been for the Equisetum 

 (see cut below). 



Photograph by D. B. Church 



A TURF FORMED BY SEEDLINGS OF DESCHAMPSIA C^SPITOSA. 



These came up under the protection of a rank growth of the pioneer horsetail 

 which has been cut away in the foreground to expose the grass. 



HARD COMPACT BEDS OF ASH. 



Returning now to the areas occupied by fine grained ash, one 

 other set of conditions rather commonly encountered must be 

 described. Where masses of fine terra-cotta ash are so situated 

 as to be kept well drained, the particles "set" together so as to 

 form a compact hard mass very unfavorable to plant growth. 

 Laboratory experiments with this material show that seedlings 

 grown in it are at a considerable disadvantage as compared 

 with those in the coarser grained ash. The difficulty is probably 

 due to lack of aeration, as well as to the mechanical obstacles 

 to root extension offered by such a compact hard "soil." The 

 analyses show that it is not due to any deleterious chemical in 

 the material. Buckwheat, which was planted in an area of 



