282 Proceedings of Indiana Academy of Science 



Betula lutea, Toxicodendron vernix, Samhucus racemosa, Cornus cana- 

 densis, Cofitis trifolia, Cypnpedium candidum and Cypripedium hirsu- 

 tiiiw. 



These two wooded swamps are about two and a half miles apart. 

 Between them is an unwooded swamp or marsh, in places quite wet 

 where the conspicuous plants are sedges growing in tussocks, Spiraea 

 tomentosa Rosa Carolina, and a few examples of Habenaria cHiaris and 

 Gentiana sajjonana. 



Just north of the Mineral Springs swamp is an interdunal pond 

 and meadow called Little Lake^ The striking plants of this wet meadow 

 are RJiynochospora vuicrostachya, Eriocaulon septangulare, Drosera in- 

 termedia, Rhexia virginica, Polygala cniciata and Utricularia vulgaris. 



Just south of the Mineral Springs tamarack swamp and continuous 

 with it is a very wet quaking bog. The conspicuous plants in it are 

 various rushes, Parnassia caroUniana, Sarracenia ^nirjnirea, Oxycocciis 

 macroca.rpus, Gentiana detonsa, Gerardia purpurea. Lobelia kahnii and 

 Decodon verticillata. 



It was impossible to determine soil and water acidities through- 

 out the entire extent of all these areas, but a few characteristic por- 

 tions of each were selected and acidities determined in them. In addi- 

 tion to these some determinations were made of the soil of the wooded 

 dunes, of the fore-dune area, of the water of Lake Michigan, of an 

 artesian well and of a pump well. 



Acidities of these places are given in the following table expressed 

 in terms of what Wherry calls specific acidity or alkalinity rather than 

 in terms of the Pn values. A minus sign is used to indicate alkalinity 

 in the table (Table I). The specific acidity figure gives a better idea of 

 the relative acidities and has the merit of yielding figures of appreciable 

 size. Thus the difference between Pj{7 (neutral) and Pjj6 or Pj^8 

 appeals to the eye as one unit, yet the latter are respectively 10 times 

 more acid or more alkaline than the former. 



Table I. Average Specific Acidities of Soil and Water in Dunes 

 Region of Porter County. 



Lake Michigan — 10 



Artesian well, opposite Tremont, near Prairie Club Trail — 10 



Pump well at Drive-Inn Cottage, Waverly Beach 10 



The same water after boiling — 10 



^ As Betula papyrifera. Thuja oecidentalis and Cornus canadcnnis in this swamp aio 

 close to their southern limits in this general region and are essentially northern plants 

 a number of tcmpcratuic readings of the soil were made on July 22, 1'923, to see whether 

 there were any local differences in temperature between the Tremont and the Mineral 

 Springs swamps. The readings were made with a centigrade chemical thermometer about 

 a foot long and inserted into the soil its entire length. The results of these readings 

 showed a soil temperature in each swamp of about 18° C. Possibly the readings should 

 have been taken at greater depth and have been made on a series of days. Those ob- 

 tained were all made on one day, in the Tremont swamp earlier in day than in the 

 Mineral Springs swamp which botanically should have been the cooler. The air 

 temperature in the shade at 11 A. M. was 29° C. and at 3 P. M. 26° C. 



' Rand McNally's Map of Indiana Dunes by P. S. Goodman. 



