PERIODICAL LITERATURE 915 



Thuya plkata.— — —\ duration of sreen color, ; Sargent and Sud- 



- "^ 4-7 ^ 2-5 



worth, 3 ; mature and shaded longer than saplings or open ; dry 

 climate and peat bog longer; browned leaves remain 2-3 years in 

 typical moisture conditions ; 4-6 years in bogs. 



2—12 



Tsiiga hcteropJiylla. ; mature longer than saplings under same 



conditions ; slow-grown shaded saplings under mother trees longer 

 than these ; saplings in moist climate longer than in dry ; converse 

 for mature ; slow-grown bog saplings show two maxima in each of 

 the three curves, the first occurring in the fourth, the second in the 

 sixth and seventh years ; variations of toxicity ; mature bog trees 

 normal maxima ; both longer in ordinary soil. 



Rhamnus purshiana. Some leaves persist till May. 



Arbutus menziesii. Leaves begin to fall in June of their second year. 

 Second growth in late summer of smaller, lighter-colored leaves 

 makes appearance of two seasons. 



Reprint from Ai)ierican Journal of Botany, March, 1917, pp. 145-60. 



SOIL, WATER, AND CLIMATE 



Professor R. de C. Ward points out that the 



Rainfall distribution of the rainfall during the season is 



Types of importance directly and indirectly in agricul- 



of ture, by furnishing water at the right time and 



United by influencing soil conditions ; in irrigation and 



States power works, by influencing size of storage 



reservoirs and loss by evaporation ; in pleasure 



and health resorts depending on seasonal conditions. 



Ward revises the classification of rainfall types in the States by 

 Greeley (6 types) and Henry (10 types). 



The basis for differentiating the eight main and various subtypes 

 of the author was found by constructing composite curves, showing 

 the amounts of rainfall from month to month, the composite character 

 being secured by combining the records of five or six stations in the 

 same general district. A small map shows the distribution of the types. 

 The type which covers the largest extent, namely, practically all the 

 territory east of the hundredth meridian, except the Gulf Coast, is 

 called the Missouri type. This main type covers the northern plain, 

 with variations to the eastward. Its general characteristic, favorable 



