APPENDIX B: 

 EXTERNAL MEASUREMENTS 

 OF NANOMIAN PNEUMATOPHORES 



It is of interest to know the volume of the pneumato- 

 phores of Nanomla. Several series of these floats were 

 measured by ocular micrometer at 27x; a representative 

 tabulation is presented in table B-l. Actual volumes of the 

 pneumatophores were obtained by measuring meniscus 

 displacement of a drop of water in a glass capillary of 

 diameter just sufficient to accommodate the float being 

 measured. The difference in length of the drop of water 

 before and after introduction of a float gave the true float 

 volume. Volumes calculated as spheres (diameter obtained 

 by averaging length and width) were found to be high over 

 displacement volume by a factor of 1. 5 to 3, while volume 

 calculated as prolate spheroids are more uniformly low by 

 a factor of 0. 5 to 0. 8 (table B-2). 



The possibility that the severed floats were imbibing 

 or extruding water through their basal areas where adhering 

 fragments of stolon had been removed was considered. This 

 was checked by constructing a small solid glass model which 

 was measured in the usual way, and whose volume was de- 

 termined by the capillary displacement method. The ratio 

 of volume calculated as a prolate spheroid to that actually 

 measured by the capillary method was 0. 7. This is very 

 near to the average for this ratio given in table B-2. There- 

 fore, the capillary displacement method for determining 

 the volume of intact floats was deemed reliable. 



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