Development of the Vegetation of New York State 157 
species on Shawungunk Mountains. Sheep laurel (Aalmia 
angustifolia) a typical bog plant, occurs on the sand barrens 
at Plattsburgh and Albany. So with black chokeberry 
(Aronia melanocarpa) swamp golden rod (Solidago uligin- 
osd) running swamp blackberry (Rubus hispidus) and others. 
These facts of distribution seem to point to a similarity of 
conditions as respects the soil factors in bogs and sand bar- 
rens, particularly where the sands lie compact and poorly 
drained. In this connection I would express the conviction 
that the tendency toward bog formation is greater in basins 
which lie in sand regions (e. g. Phoenix bog, Bean pond) 
than in those lying in regions of clay, silt, fine gravelly clay, 
ete. 
The water deficit which is taken for granted in sand soils 
seems to have its equivalent in bogs. Schimper * called bogs 
phystologically dry habitats, arguing that some factor or fac- 
tors retarded water absorption by bog plants. The presence 
of bog toxins may operate in this connection. Although the 
former assumption of the presence of ‘“ free humic acids” 
seems no longer applicable, it appears difficult to explain the 
dominance of heath-shrub vegetation in both bogs and sand 
barrens unless we assume the presence of an acid soil or an 
acid-reacting substratum im each case. Possibly the case 
could be explained by the so-called adsorption phenomena 
displayed by Sphagnum, sand soils, kaolin, ete., in which it 
appears that from a certain neutral solution as for example 
sodium cloride, the base is taken up, “ adsorbed,” by the 
Sphagnum, sand, ete., leaving the acid component free to 
show its reaction —as for example on litmus paper.” Re- 
calling the work of Coville (experiments in Blueberry Cul- 
ture, /. c.) in which he demonstrated the presence in heath 
plants (certain species, and inferentially in all of the EHri- 
cales) of mycorhizal fungi, and that these fungi can exist 
only in an acid medium, it appears warranted to use heath- 
ie Ll. ¢., page 2. 
2Harris, J. E. Some adsorption phenomena in soils and kaolin. 
Jour. Physical Chem., 18:No. 4, pp. 355-372. 
