ACIDITY OF BOGS AND SANDY UPLANDS. 35 



in whicli large quantities of leaves, chiefl}- oak, have been clumped 

 for many years. Samples taken there in late November, 1909, show 

 an acidity in the case of freshly fallen leaves of 0.4 normal; in leaves 

 apparently 1 year old, 0.006 ; and in leaves about 2 years old, 0.002. 



A condition of great interest was found in one of these piles of 

 leaf mold which was several years old. It was mellow and black, and 

 the evidence of leaf structure had disappeared. When submitted to 

 the phenolphthalein test it proved to be alkaline, and upon chemical 

 examination it was found to contain 3.55 per cent of lime (CaO). 

 In this case decomposition had progressed so far, it is suggested, that 

 the lime in the leaves, remaining constant in amount and probably 

 having been changed to a more soluble state, had neutralized the 

 remaining acidity. The material, then becoming alkaline, had pro- 

 ceeded to decompose with greater rapidity, until a real mold had been 

 formed. 



The condition here observed is doubtless the same as that which 

 occurs in the drained bog, or so-called " muck," lands of Michigan. 

 When first plowed they will grow only certain acid-resistant crops, 

 such as buckwheat or potatoes, but later, as their acidity disappears, 

 they come to attain a very high degree of fertility. It is probably a 

 phenomenon of similar character Avhich is taking place in the drained 

 swamp lands of the lower Sacramento River in California, where the 

 soil, which is already in a state of remarkable fertility, is becoming 

 increasingly alkaline. 



Here allusion may be made to another phenomenon, that of the 

 occurrence of the swamp blueberry and certain other plants, such 

 as the purple lady's-slipper {Cypripedivm acaide) and the swamp 

 honeysuckle {Azalea nndifora)^ in two kinds of situations — one a 

 peat bog, the other a sandy, well-drained, and often dry upland. The 

 favorite explanation of this phenomenon among botanists is that these 

 plants are naturally adapted to the drier situation and that in the bog 

 they find a situation of " physiological dryness," or vice versa. 

 While the existence of physiological dryness in peat bogs is not 

 questioned, the explanation that a bog plant finds an upland situation 

 congenial because it is dry certainly will not answer for the blue- 

 berry. Its occurrence in these two habitats is dependent on the 

 acidity of both situations. These experiments have shown that no 

 amount of dryness will make a blueberry flourish in an upland soil 

 if that soil is not acid. 



(9) Fob active growth the swamp blueberry requires a well-aerated soil. 

 Conversely, the swamp blueberry does not continue in active growth 

 IN a soil saturated with water. 



In its natural distribution the swamp blueberry does not grow in 

 the lower, wetter tyj^e of bog. In a typical leatherleaf {Chamae- 

 daphne calycidata) bog, for example, the swamp blueberry is found 



193 



