1920] 



SNOW— DIAPHRAGMS 



30I 



except to show that the change from air to water was accompanied 

 by a marked rise in temperature (fig. 1). This experiment indi- 

 cates that water may not be as important a factor in the growth 

 of Scirpus validus as temperature. This is probable because the 

 growing region is protected from the surrounding medium by a 

 very closely fitting sheath of scale leaves. 



Effect upon distance between diaphragms. — The distance 

 was measured between many diaphragms and the average taken. 

 As it was found that the diaphragm distance varied with the 

 distance from the tip, the culms were divided into decimeter 

 sections, so that the measurements taken in corresponding sec- 

 tions of the different culms, and in different sections of the same 



culm, might be compared. 



TABLE III 



Distances in mm. between diaphragms of Scirpus validus grown in 



WATER AND IN AIR 



Pot 



Culm no. 



dm. 

 from tip 





A 



E 



CC 



3 

 5 



DD 



3 



3 



1-2 dm. 

 from tip 





3 5 

 2.6 



27 



2-3 dm. 

 from tip 



3-4 dm. 

 from tip 



3 80 





2.5 

 4.0 



1.6 



2.4 

 1.9 



1.6* 



3-6 

 3-o 



4.8 



4 4 



3-8 5 t 



4-5 dm. 

 from tip 



4.6 



8.2* 

 3.0* 



3-9t 



* Two chambers in same section. 



t May extend over decimeter boundaries. 



In table III the heavy type indicates parts grown in water, 

 and the remaining figures indicate those grown in air. Read 

 horizontally, the variation in a single culm, from tip to base, may 

 be seen. Read vertically, the variations in the same region of the 

 different culms are shown. As it was impracticable, from the data 

 at hand, to calculate the rates of growth for the decimeter regions, it 

 was not possible in this experiment to correlate the rate of growth 

 with the distance between diaphragms. 



Experiment 



necessary 



sxperiment £ 

 ore in April 



that temperature control was 



* • * A. 



:xperiment 



