BOOKS AND CURRENT LITERATURE 



plants had taken on a green color {-omparable with that in plants ex- 

 posed to full sunlight for six hours. According to Stocklasa's observa- 

 tions the synthesis of chlorophyll proceeds best with a wave length of 

 575 to The protoplasm of the epidermal cells was affected by 



long exposures so that certain of the cells became brown, without injury 

 having been done to chlorophyll in the subjacent parts. Many flowers 

 were found to be wilted and some of them even to be killed after a two- 

 hour exposure. Leaves appear to be more resistant to injury than do 

 flowers, and out of door plants more resistant than those grown under 

 glass. The protoplasm of bacteria responds more quickh' to illumina- 

 tion with ultra-violet raj's than that of phanerogams. Azotobader 

 shows itself to be verj' susceptible, being killed by an exposure of eight 

 to ten seconds at a distance of 10 cm. If, however, a screen is used, 

 cutting out all the rays less than 240fxfx in length, not all of the organisms 

 are killed after an exposure of five seconds. — Frederick A. Wolf. 



Ohio Peat Deposits. — The Geological Survey of Ohio has recently 

 issued a volume on the origin, formation, and uses of the peat deposits 

 of that state.^ The book contains a discussion of the general properties 

 of peat, its distribution in the United States, and its occurrence in Ohio 

 by counties. The fourth chapter is by C. A. Davis, of the U. S. Bureau 

 of Mines, on the economic utilization of peat. This is followed by three 

 chapters on the history and development- of Ohio peat deposits, and four 

 chapters on the causal and limiting factors in the process of peat forma- 

 tion. In addition to the large amount of detailed information concern- 

 ing the bogs of Ohio, it contains altogether the most complete discussion 

 of the northern type of peat deposits that has appeared in this country. 

 The author has brought together much of the literature bearing on bog 

 plants, their migrations, and their relation to ecological factors, as well 

 as the results of his own studies of the connection between bacteria 

 and the toxicity of bog solutions. His general conclusion is that the 

 well known toxic properties of bog soils are the result of bacterial activi- 

 ties. If the data presented are not always exclusive of other interpre- 

 tations, they contribute materially to our knowledge of this phase of 

 bog soils, and that most interesting of all agricultural problem.s — soil 

 fertility.— E. N. T. 



' Dachnowski, A., Peat Deposits of Ohio. Geological Survey of Ohio, Fourth 

 Series, Bull. 16, pp. 424, figs 29, pis. 8, map. Columbus, 1912. 



