BY A. H. S. LUCAS. 679 



action for potash is of course almost equally striking " [as that 

 for iodine] "but the difference is of interest: much of the 

 potassium chloride effloresces out as the plant dries, while no 

 iodine is demonstrated in the effloresced salt." 



In view of the above, Mr. Steel's complete analysis of an 

 efflorescence undoubtedly derived solelv from thealfja? themselves, 

 is of great value. 



Mr. Hongland does not speak of mannitol, or of any other 

 organic substance in the efflorescence, but, I.e., p. -1 7, speaking of 

 tlie non-nitrogenous organic substances present in the kelp, he 

 says, 'Ver\' little information isobtainable for these groups, and 

 there are no satisfactory chemical methods available for their 

 study. In general, complex mucilaginous polysaccharines aie 

 characteristic of marine algjp, replacing the starch, cellulose, and 

 simple sugars of most land-plants." I do not know whether 

 mannitol has been found in the dried weed. Stanford regarded 

 it as an after-product produced by fermentation!* In the case of 

 the New Zealand plants, the efflorescence is still forming (May, 

 1916), quite a large fresh crop of crystals having appeared in tlie 

 interval from June, I 9 ' 5. It seems improbable that a fermenta- 

 tion could continue for five years and a lialf under dry condi- 

 tions. I imagijie that the efflorescence is a purely physico- 

 chemical phenomenon. 



It would be premature to discuss the bearing of the result of 

 the analysis of this efflorescence upon the subject of the meta- 

 bolism of kelps. 



