Periodical Literature. 253 



campus of the State University. The differences in temperature, 

 acidity, osmotic pressure, position of the water table, and the 

 amount of available food salts in the various zones are not 

 sufficient to limit the distributional relationships. 



The author thus summarizes his findings : 



Physiological investigations of peat soils have brought out 

 clearly the fact that the character of the obligate bacterial flora 

 and the nature of the organic compounds produced, form a very 

 important factor in the relative fertility of peat soils, in the 

 causes of vegetation succession, in the distributional and genetic 

 relationships of associations, and in the characteristic xeromorphy 

 of both ancient and modern bog vegetation. 



In view of the widely differing behavior of agricultural varie- 

 ties in a bog water solution, and the interesting observation that 

 plants of the same species respond differently to the same solution, 

 the conclusion is inevitable that here the source of the difference 

 must logically be looked for, not in the solution alone, but in the 

 conditions of the plants as well. 



Since certain of the organic compounds eventually penetrate 

 the protoplasmic membrane of absorbing organs and inhibit 

 growth, it is evident that much importance must be ascribed to 

 the influence exerted upon the plasmatic membrane, to the con- 

 sequent differences in its diosmotic properties, and to the patho- 

 logical changes induced, which accompany the absorption of the 

 injurious substances. The phenomena of absorption and toler- 

 ance, however, deal plainly not with osmotic pressure relations so 

 much as with considerations of the permeability of the absorbing 

 protoplasmic membrane, its power of endurance, and its ability 

 by enzymatic action either to absorb and assimilate or to trans- 

 form injurious bodies into insoluble, impermeable compounds. 



The organic disintegration substances in peat soils, while in- 

 hibitory to agricultural plants, have little or no effect on certain 

 xerophytic plants. These organic substances play the differen- 

 tiating role and are a cause of the infertility of peat deposits even 

 when the amount of air and water in the soil is abundant and the 

 temperature and humidity conditions are favorable to growth. 

 These facts have an important bearing on the value of peat land 

 to agriculture. 



Tlu Nature of the Absorption and Tolerance of Plants in Bogs. Vhe 

 Botanical Gazette. December, 1912. Pp. 503-514. 



