IODINE IN MARINE FLORA AND FAUNA 63 



SESSIONAL PAPER No, 39b 



The results obtained for the thyroids of Squalus permit a direct comparison 

 with those for mammalian tissue in determining the relative amount of iodine, 

 and of thyroid tissue, per kilogram of body-weight of the whole animal. The 

 total amount of thyroid tissue obtained from 66 female fish was 1.459 grams. 

 Ten of these fish selected at random gave an average weight of 3.8 kg. The 

 average iodine content in the dried thyroid tissue was 0.195 per cent. The 16 

 male fish yielded 0.169 gram dried thyroid containing 0.224 per cent, iodine. 

 Ten of these fish selected at random gave an average weight of 2.5 kg. 



These figures may be compared with those obtained from analyses of twelve 

 dogs (ordinary laboratory animals of no particular variety) which I have already 

 published 0) in which the total weight of the dogs was 191 kg., they contained 

 14.33 grams thyroid tissue, containing 0.95 per cent, iodine. Hence: 

 Squalus sucklii (female) contains per kg. body weight . 0058 g. dry thyroid tissue 



containing 0.000011 g. iodine. 

 Squalus sucklii (male) contains per kg. body weight . 0042 g. dry thyroid tissue 



containing . 000009 g. iodine. 

 Canis contains per kg. body weight . 075 g. dry thyroid tissue containing . 00007 g. 



iodine. 



The figures indicate that both iodine content and amount of tissue are smaller, 

 but of comparable order. If the figures obtained by me for Scyllium canicula 

 can be regarded as comparable for body weight (I obtained the value 1 . 16 per 

 cent, iodine in dry thyroid tissue (^), but have no data as to the weight of 

 the fishes from which the tissue was obtained), this species would give a much 

 closer figure to that for mammals. The cause of the difference obtained for the 

 two species of dog-fish may be a seasonal variation (the Scyllium thyroids were 

 obtained in winter), or a different diet containing less iodine, or the difference 

 may be specific for the two species. Further work is indicated in this direction. 



Discussion of Results. 



In considering the results for algae, it becomes evident that while every species 

 examined contained iodine in detectable amount, only those of two families Lami- 

 nariaceoe, and Delesseriaceoe, contained amounts of the order of . 1 per cent. 

 The results are in substantial agreement with those obtained by Turrentine (») 

 for many of the same species of algae obtained further south, with the exception 

 that many of his values are distinctly higher, in spite of the fact that his analytical 

 method should lead to lower rather than higher figures. This is probably traceable 

 to the fact that the specific gravity of the waters near Nanaimo is very low (due 

 to the influx of large bodies of fresh water, such as the Fraser River) , with a con es- 



' ./. Biol. Chem., 1914, 16, 472. 



' Biochemical J., 1913, 7, 468. 



3 U. S. Senate Document, No. 190, 62nd Congress, 2nd Session, 1912, p. 220. 



