88 PROCEEDINGS OF THE ACADEMY OF [March, 



drift, averaging minimacid in reaction. A few Ericaceae, notably 

 Rhododendron maximum and Kalmia latifolia, grow there naturally, 

 and it has been found possible to introduce many other species. 

 The acidity found seems rather low, judging from what has been ob- 

 served in the course of these studies, for these plants to make the 

 best growth, but peaty material of sornewhat more acid reaction — 

 subacid — is being brought from the Pocono region, and mixed with 

 the native soil, the result being highly satisfactory. At most other 

 places within the glaciated area the drift is dominantly siliceous, 

 and the soil reactions more strongly acid, Ericaceae being wide- 

 spread and abundant at many points. 



It was particularly desired to obtain data as to the behavior of 

 ericaceous plants at or near a contact of a siliceous rock with a lime- 

 stone; and one such locaUty was found, near the country club, 

 some 3 km. (2 miles) east of Williamsport, Lycoming County. 

 Near the main road (from Williamsport to Montoursville) there is 

 an old limestone quarry; on the waste ground around it is a dense 

 thicket of various shrubs bearing small, juicy fruits; the call of 

 catbirds from the thicket suggesting how these shrubs may have been 

 introduced. There were one or more species of Celtts, Prunus, 

 Crataegus, Rhus, Celastrus, Samhucus, etc., present; but in spite of 

 thorough search, not a single member of the Ericaceae could be found, 

 although colonies of these plants, from which the birds no doubt 

 obtain much food, are present within a few hundred meters. Evi- 

 dently the seeds of the Ericaceae, when they fall into the limestone 

 soil, either do not germinate at all, of if they do, the young plants 

 soon succumb. Tests of the soil showed its reaction to vary from 

 neutral to minimalkaline. 



Going north from this quarry, around the end of a golf course, 

 the limestone rock gives way to shale and this in turn to sandstone, 

 a thin oak woods spreading over the contacts of these formations. 

 As the limestone is receded from, the soils become more and more 

 acid, and Ericaceae gradually appear. The first species was found 

 to be Vaccinium vacillans; its soil proved to be minimacid. Gay- 

 lussacia baccata and Azalea nudiflora come in a short distance fur- 

 ther on; their soils being minimacid to subacid. On reaching the 

 sandstone formation Ericaceae appear in abundance, the above 

 mentioned species being still present, and in addition Kalmia lati- 

 folia, GauUheria procumbens, Epigaea repens and Vaccinium corym- 

 bosum. Various species of pine trees, and other acid soil plants, 

 such as Lupinus perennis, come in here also; and tests of the soi- 



