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SCIENCE 



[N. S. Vol. XXXIX. No. 1010 



mis, thus connecting the intercellular spaces with 

 the outer air. By this method transpiration was 

 foimd to decrease proportionally as relative hu- 

 midity increased. The straight line relation led 

 to the conclusion that a relative humidity of 105 

 would be required to reduce transpiration to zero. 



C. S. Scofield, "Chinese Wild Eice," with lan- 

 tern (to be published later). 



Dr. P. Spalding, "Present Status of the White 

 Pine Blister Rust," with lantern (to be published 

 as a bulletin of the Department of Agriculture). 



R. Zon, ' ' Meteorological Observations for Pur- 

 poses of Botanical Geography, Agriculture and 

 Forestry, ' ' with lantern. 



The inadequacy of the present climatic data for 

 the purposes of botanists lies not so much in the 

 kind and character of observations that are being 

 recorded as in the manner of their classification, 

 their grouping and computing. 



To properly understand plant life, it is essential 

 to group meteorological data by actual periods of 

 growth and rest. During each of these two periods 

 plants react to temperature of the air in an alto- 

 gether different way. The temperature records 

 of the temperate region of the United States 

 should be computed separately on the basis of the 

 normal monthly mean not reduced to sea level for 

 the period of rest or the period of growth, and in 

 some localities also for a third period, the hot 

 period. The period of rest should include all 

 months having a normal mean temperature of 48° 

 F. or less. The period of growth should be in- 

 cluded, all months having a normal monthly tem- 

 perature of from 50° to 72° F. The hot period in 

 temperature latitudes should embrace months with 

 a normal average temperature of more than 72° F. 



A map showing localities with the same dura- 

 tion of the periods of growth and rest has been 

 tentatively prepared. 



Aside from monthly mean temperatures the 

 average temperatures by periods of ten days (de- 

 cades) are also desirable, and also the mean tem- 

 peratures for periods when the ground is covered 

 with snow and periods when the ground is bare. 

 Similarly, the mean temperature for each period 

 during which certain winds prevail. 



Summation of temperatures, as suggested by 

 Bussengo and de Candolle, do not indicate the ac- 

 tual requirements of plants for heat, since they 

 overlook the existence of an optimum temperature 

 for the development of each plant. 



Groups of days with a given temperature are 

 considered preferable, and the following classifi- 

 cation is suggested: 



1. Freezing days, with a daily average of 32° 

 or less. These are further subdivided into: (o) 

 Freezing days without thawing; (6) freezing days 

 with thawing. 



2. Cold days, with an average daily temperature 

 ranging from 32° to 40° F. This group should be 

 further divided into: (o) Days with frost; (6) 

 days without frost. 



3. Cool days, with an average daily temperature 

 from 40.1 to 50° F. This group should be divided 

 into: (a) Days with frost; (6) days without frost. 



The paper discussed also the temperature of the 

 soil, humidity of the air, precipitation, snow cover, 

 soil moisture, sunshine and barometric pressure. 



P. L. RiCKER, 



Corresponding Secretary 



THE ST. LOUIS ACADEMY OF SCIENCE 



"Mounds and Mound Builders" was the sub- 

 ject of a lecture by Dr. H. M. Whelpley, at the 

 February 16 meeting. It was illustrated with 

 lantern slides. 



The lecture dealt particularly with the mounds 

 of niinois and Missouri. Strictly speaking, there 

 was no race of mound builders, mounds having 

 been built by primitive peoples, the world over. 

 Indian mounds were discussed and their various 

 types explained. The important Cahokia Group, 

 in Madison Co., 111., was considered in detail. 

 The general arrangement and location of these 

 mounds was clearly shown in a series of maps of 

 the Long Lake, Bluff, Forest Park, St. Louis, 

 Cahokia and other subgroups. It was shown that 

 at the time these mounds were built, the Missis- 

 sippi River probably was close to the Dlinois 

 bluffs, so that they were all originally on the west 

 side of the stream, a fact which helps to explain 

 their similarity. From their nature, it is evident 

 that many years must have been required for con- 

 struction and the archeological evidence points to 

 their having been built by an agricultural people, 

 quite different from the Cahokia Indians whom 

 white men found here. Some views as to their 

 possible use were considered. The plan of 

 Monks', or better, Cahokia Mound was discussed 

 and a number of early drawings and diagrams 

 were thrown upon the screen. The known history 

 of this mound was reviewed. Attention was called 

 to the artistic possibilities of mounds and the 

 agencies tending toward their destruction were 

 emphasized. The speaker closed with a plea for 

 the preservation of these wonderful relics of earlier 

 ag€s. G. O. James, 



Secretary 



