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ZOOLOGY: L. R. GARY 
In order to determine the amount of material contributed to reef 
formation, during any given time, by the gorgonians, three factors must 
be taken into consideration: first, the amount of Kme held as spicules 
in the tissues of these colonies; second, the bulk of the gorgonians pres- 
ent on any reef area; and third, the number of colonies which will set 
free their spicules through the death and subsequent disintegration of 
their coenenchyma. 
1. Spicule content. In making the determination of the amount of 
spicules for any species the colony was removed from the reef without 
injury to any portion except the expanded base, which was always dis- 
carded as it was difficult to separate from it fragments of limestone from 
other sources. The colony was then weighed while still wet, cut into 
small pieces and the living tissue destroyed by treatment with a cold 
25% solution of caustic soda. When the organic material had been 
dissolved the spicules were washed in rain water until no trace of or- 
ganic matter remained, collected on a weighed filter, dried in a water 
bath kept at 100°C. and after cooling in a dessicator to room tempera- 
ture, carefully weighed. By this procedure the proportion of spicules 
to the fresh weight of the colony could be estimated for any collection 
of gorgonians by simply separating the several species and determining 
the weight of each one. 
As previous studies upon the growth rate and ecology of the gorgoni- 
ans of this region had shown that at least nine-tenths of the bulk of 
these organisms on any reef is made up of not more than twelve species, 
the spicule determinations were consequently restricted to these forms. 
The results of analyses of the twelve most common species is shown in 
the table in which the figures given represent the average of five determi- 
nations for each species. 
AVERAGE WEIGHT IN POUNDS AND PERCENTAGE OF SPICULES IN GORGONIAN COLONIES 
Average 
Species of gorgonian weight 
of colonies 
Briareum sp 2.00 
Eunecia rousseaui 1 . 00 
Eunecia crassa 0 . 30 
Plexaura flexuosa 1 . 00 
Plexaura homomalla 1 . 50 
Pseudoplexaura crassa 2 . 50 
Percent 
spicules 
Species of gorgonian 
Ajerage 
weight 
of colonies 
Percent 
spicules 
26.66 
Plexaurella dichotoma . . . 
. 0.75 
35.86 
35.60 
Plexaurella sp 
0.75 
24.92 
22.66 
Gorgonia flabellum 
1.00 
22.33 
30.66 
Gorgonia acerosa 
3.00 
19.75 
27.41 
0.25 
35.05 
21.48 
0.25 
25.83 
of spicules for all species 27.40% 
The determinations given above were made primarily to afford a basis 
from which the spicule content of large masses of gorgonians could be 
calculated and in order to have a check for these computations a series 
