PACIFIC COAST KELPS 173 



SESSIONAL PAPER No. 38a 



stipe), while that of the float is very constant. There is therefore an evident and 

 marked difference between the composition of the float and that of the stipe; to 

 microscopic examination they appear very similar in structure. 



From the fact that young plants of Nereocystis usually contain more iodine than 

 full grown ones, it follows that plants obtained during early summer, when the 

 majority are not full grown, will give a greater average yield of iodine for the same 

 weight, than plants obtained later in the year. (The total bulk of the plant increases 

 rapidly, however, during the final stages of growth, so that with a lesser average con- 

 tent, full grown plants will yield a greater quantity of iodine. For harvesting for 

 commercial purposes, also, Nereocystis, for various reasons set forth in an earlier 

 report, should not be cut before July.) 



Comparison of the figures given for full grown plants of Nereocystis with those 

 given by other observers for the same species from other localities does not reveal any 

 differences more marked than those in the last table above, and does not give any 

 definite evidence that latitude is a factor in iodine content as has sometimes been 

 suggested. 



University of Manitoba, 

 June 30, 1915. 



