Hill: Penobscot Plants. 291 



forms and can maintain themselves, and even advance, in 

 areas with a mnch smaller percentage of basic material. 

 Even these plants, however, avoid the loose soil of the dry 

 coniferons forests and the acid bogs. 



The occnrrence of the above mentioned species on a ser- 

 pentine area brings us to another problem. Usually a 

 serpentine region is characterized by a great paucity of 

 vegetation and the presence of peculiar species which are able 

 to** utilize, as food, the magnesium, an element which is ex- 

 tremely toxic to most plants. At first sight it would appear 

 that here was a condition directly opposed to the general rule. 

 Far from being a sterile area almost devoid of vegetation, 

 this area has the ricliest flora of any part of the region. It 

 is apparent that some other substance must be present in the 

 soil to counteract the effect of the magnesium. An exami- 

 nation of the underlying serpentine rock shows it to be filled 

 with numerous veins of calcite which readily decomposes and 

 furnishes lime to the soil. The work of Von Raumer' and 

 of Loew" has demonstrated that calcium exerts an antagonistic 

 action on magnesium and may even destroy its toxicity en- 

 tirely. In this connection Osterhout" states that "a single 

 Ca ion acts as an antidote to from 20 to 100 ions of 

 x^a,K,NIl4, etc." The large amount of calcite present in 

 this serpentine would easily be sufiicient, not only to counter- 

 act the magnesium, Imt also to render the soil extremely basic 

 and fertile. 



Von Raumer. Calcium und Magnesium in der Pflanze. Landw. 

 Versuchsst. 19: 253-280 (1883). 



Loew & May. The Relation of Lime and Magnesia to Plant 

 Growth. U. S. Dept. Agr. Bur. Plant Ind. Bull. 1 (1901) ; Loew. 

 The Physiological Kole of ^lineral Nutrients in Plants. U. S. 

 Dept. Agr. Bur. Plant Ind. Bull. 45 (1903). 



Osterhout. Some Chemical Relations of Plant and Soil. Science 

 N. S. 36: 571 576 (1912). 



