The position of the meniscus in the volume -displace- 

 ment measurements could be read with a hand lens to ±0. 2 

 mm, an error of approximately 1. 5 percent for an average 

 water-drop length of 15 mm in a capillary of 1. 85 mm ID. 



If, for example, in the case of pneumatophore num- 

 ber 8, table B-2, the estimated volume was a maximum of 

 9 percent greater than that shown and the displaced volume 

 a maximum of 2 percent less than that shown, the resultant 

 increase in the ratio of calculated to displaced volume in 

 this case changes from 0. 064 to 0. 072, a maximum dis- 

 crepancy of only 12 percent. 



TABLE B-2. EVALUATION OF PNEUMATOPHORE VOLUME MEASUREMENTS* 



Pneumatophore** 



Length 

 (mm) 



Width 

 (mm) 



Volume Estimated as 



a Prolate Spheroid 



(mm 3 ) 



Volume Determined 



by Capillary 

 Displacement (mm 3 ) 



Ratio 

 (Est. Vol.: 

 Dis. Vol.) 



1 



4.3 



1.2 



3.2 



3.8 



0.8 



2 



4.3 



1.5 



4.8 



8.0 



0.6 



3 



3.6 



1.2 



2.6 



4.9 



0.5 



4 



3.9 



1.2 



2.8 



4.4 



0.6 



5 



4.2 



1.8 



6.8 



10.5 



0.6 



6 



4.0 



1.4 



4.1 



7.9 



0.5 



7 



4.0 



1.6 



5.5 



7.3 



0.7 



8 



4.8 



1.5 



5.6 



8.7 



0.6 



9 



4.3 



1.6 



5.9 



7.1 



0.8 



10 



4.2 



1.3 



3.9 



6.3 



0.6 



Glass Model 



9.3 



0.8 



3.1 



4.6 



0.7 



*Dimensions were measured with an ocular micrometer at 9x, and an accuracy of +0.1 mm. 

 **These were preserved pneumatophores, collected July 1963. All pieces of attached 

 stolon were removed. 



43 



