96 The Plant World. 



the compound ears are to be considered as fa'sciated this number 

 would be considerably increased. So high a percentage is not 

 obtained when fasciation is considered by ear, showing that the 

 fasciation does not always extend to every ear of the plant. At 

 the same time a comparison of the results obtained from No. 

 11410, a non-fasciated ear, and those from No. 11310 and No. 

 11510, both fasciated ears, show that fasciation is not a matter 

 of mere accident but one of inheritance and subject to the same 

 laws as are other characters. 

 University of Michigan. 



A RADIO- ATMOMETER FOR COMPARING LIGHT 



INTENSlTlEvS. 



Burton Edward Livingston 



In attempting to measure and compare the external con- 

 ditions which influence the behavior of plants there has been 

 brought out a striking relation between the plant population of 

 certain habitats and the evaporating power of the air, the latter 

 being measured and automatically summed by the porous cup 

 atmometer. * But the rate of water loss from plants is usually 

 more affected by sunshine than is the corresponding rate from 

 the porous cup, so that the instrument, as heretofore arranged, 

 fails to give a true measure of all the factors that tend to remove 

 water from the aerial parts. The same is true of the rate of 

 evaporation from the soil surface, which is usually greatly in- 

 creased by sunshine. 



The foliage of ordinary plants, as well as the soil surface, 

 absorb a considerable amount of radiant energy, thereby tend- 

 ing to rise in temperature, and if water be present in the substance 

 of these surfaces (as it always is in living leaves, etc.) a goodly 

 portion of the absorbed energy becomes latent in transforming 

 the liquid water to its vapor. Thus the rate of water loss is 



♦The literature of the instrument and its '^se is given to date in Plant World 13; ) 12-118. 

 1910. Later has appeared: Brown, W. H., Evaporation and Plant Habitats in Jam- 



aica. Plant World. 13: 268-72. 1910. 



