IODINE IN CORALS. 405 



nutrients," Loew* has called attention to the possibility of 

 the presence of bromine in conjunction with the iodine and 

 chlorine in the Gorgonias. With a view to ascertaining this 

 point, I have examined very carefully a relatively large quan- 

 tity (30 grams) of the skeleton substance of Gorgonia acerosa. 

 The latter was selected because it was the richest in halogens 

 of all the species examined. The results were entirely nega- 

 tive ; not a trace of bromine was found. Lastly, the skeleton 

 substance of Gorgonia flabellum was decomposed (in quantities 

 of 50 to 75 grams) with baryta water. The method pursued 

 by Drechsel hi isolating his compound CJIgNIOa was closely 

 followed, but without success. Solutions containing organic 

 iodine compounds were obtained, but no corresponding amido- 

 acid could be isolated. Whether this result is due to the 

 relatively small quantities of the material available,! or to a 

 difference in the way hi which the iodine exists in combination 

 hi these species cannot be definitely stated. 



The preceding observations afford further justification for 

 the belief already maintained by Drechsel, that for many 

 organisms iodine is as essential an element as is chlorine for 

 others ; and that in the absence of iodine the normal nutrition 

 of the organism may be interfered with. Without some 

 assumption of this nature, it is difficult to understand why 

 organisms like the Gorgonias should store up in their horny 

 axial skeleton an element existing only in traces in sea water, 

 and apparently not entering into the constitution of the true 

 growing ccenenchyma of the animal. 



* Loew, U. S. Department of Agriculture ; Division of Vegetable Physi- 

 ology and Pathology, 1899, Bulletin No. 18, p. 21, footnote. 



t Drechsel obtained only 0.34 gram of the pure amido-acid from 50 grams 

 of gorgonin. 



