Soil and Water Reactions 283 



Dune Creek, near Waverly Beach 1 



Opposite Tremont 1 



At an intermedite point 1 



A small south tributary opposite Tremont — 10 



Fore-dune region (Calamovilfa longifolia, Primus pumila) . . . . — 7.7 



Wooded dune, exposed sand 1 



Average of several places covered with vegetation. ... 6 



Arctostapliylos uvmirsi patches, usually 3. 16 



Wooded swamp of Dune Creek, opposite Tremont 1 



Wooded tamarack swamp, opposite Mineral Springs 4 



East end of same amid Salix amydaloides , 7.7 



Open swamp between the two preceding wooded swamps 30 



Quaking bog, south edge of tamarack swamp 1.4 



Boggy meadow, south end of Little Lake {Drosera inter- 

 media, etc. ) 83 



r -10 



Water in a "pitcher" from each of four different specimens of I — 3.16 



Sarracenia purpurea 1 1 



[ 3.16 



Essentially the same phenomenon illustrated by the difference of 

 plus 10 to minus 10 in the case of the raw and boiled water of the 

 pump well was noticed in preparing the distilled water used in mixing 

 with the soils for making Pjj determinations. The water distilled was 

 from the city water supply of South Bend and issuing from the still 

 is Pjj6. Boiling this distilled water renders it Ph^- In the distilled 

 water and in the water of the pump well the acidity is evidently due 

 to presence of CO2. 



The extreme variations seen in the water of "pitchers" of pitcher 

 plants, Pjj6.5 to PjjS, may perhaps be accounted for, in part at least, 

 by the activities of mosquito larvae living in them or by an ammonical 

 decomposition of dead larvae. All four of the "pitchers" seemed to 

 contain about the same number of living mosquito larvae. 



The difference in specific acidity between the wooded swamp of Dune 

 Creek opposite Tremont and the tamarack swamp opposite Mineral 

 Springs is so small that it is probably an unimportant factor in the 

 botanical differences between them. It is perhaps due to the better 

 drainage of the former than of the latter. 



Summary. — The water of Lake Michigan and of an artesian well 

 near it have specific alkalinities of 10. This alkalinity appears to ex- 

 tend into the fore-dune area. Exposed sand of the higher dunes appears 

 to be neutral. The wooded swamp flooded and drained by Dune Creek 

 and Dune Creek itself is essentially neutral. The botanically different 

 tamarack swamp about two and a half miles farther west with no 

 very obvious drainage is slightly acid, specific acidity of about 4. A 

 boggy interdunal meadow, without drainage and with several character- 

 istics plants is distinctly acid, specific acidity of about 80. The soil 

 of wooded dunes where covered with vegetation has a low but distinct 

 specific acidity. There is a correlation between the kinds of plants 

 growing in soils or waters of different Pjj values but the differences 



