64 MARINE AND FISHERIES 



5 GEORGE v., A. 1915 



pondingly low salinity, and a probably lower iodine content (^). (To the same 

 lowered salinity may be due the total absence of Macrocystis in these waters, 

 although it is common to the south, and has been reported much fuither north.) (■). 



In the only species of alga in which different paits of the plant were systemati-^ 

 cally examined, Nereocystis liitkeana, markedly different iodine contents were 

 observed. There seems to be no regulaiity in the results so far obtained, and 

 further and more detailed work will be necessary in order to show how far varia- 

 tions exist throughout a single plant, in plants from the same locality, and in plants 

 from different localities. 



Balch, as the result of a few analyses of Nereocystis and similar forms has 

 concluded that as a rule the stipe contains more iodine than the frond (^). 

 It appears certain, both from Turrentine's figures and my own, that specimens 

 of the same species of alga from different localities may contain differing amounts 

 of iodine, but much further work including examination of both plants and sur- 

 rounding sea-water will be necessary before any definite explanation of the varia- 

 tions can be put forward. 



None of the sponges examined showed marked iodine content. There are 

 no corals obtainable in the Nanaimo district. Of the types of animal life examined 

 all except the free-floating forms and the star-fish, Pyknapodia, showed the 

 presence of iodine in detectable amount, although in one or two cases — sea- 

 cucumber, barnacle, — it was barely detectable. Hunter's method, employing 

 0.5 gram of material as in most of the above analyses, permits the detection 

 of 0.001 pel cent, of iodine with some certainty. A negative result with this 

 amount of material indicates that the iodine is not present to an extent greater 

 than . 0005 per cent. 



Macallum has shown that the iodine content of Aurelia flavidula is comparable 

 with that of the surrounding sea-water, two litres by volume of Aurelia containing 

 0.00001 gram (*). His figures for the fresh tissue do not contradict mine for the 

 dry residue, since as just mentioned. Hunter's method will not show the presence 

 of quantities of this order. 



The results obtained for the annelid worms are distinctly high. That for the 

 inner layer of the Diopatra worm tube was the highest value recorded in the whole 

 series of analyses. 



The general distribution of iodine throughout the whole of the marine flora 

 and fauna which is indicated by the results of this paper can be satisfactorily 

 accounted for by a continuous circulation of the element in a succession of living 

 organisms. Death and subsequent decay of a certain proportion of animals 

 and plants would return organic and inorganic iodine to the sea-water. Such a 



' During the five weeks stay at the Station, I made daily readings of the specific gravity of 

 the water in Departure Bay. The average of 32 daily readings was 1.015, varying between the 

 limits of 1.008 and 1.019. A few readings were taken at outside points from time to time, and 

 these approximated to the higher value. The value for normal sea-water is about 1.03. 



* See Setchell, U. S. Document No. 190, 1912, p. 135. 

 •/. Industrial Chem., 1909, 1, 777. 



* J. Physiology, 1903, 29, 213. 



