20 



potassa, and 2.7 mgr. soda. On the determination of the amount of asli 

 in the plant it was found to be 8.04 per cent, in which was 0.6 part 

 chlorine, so that the plant therefore contained in the dry matter over 

 one thousand times as much chlorine as an equal weight of the water 

 in which it was grown. 



SODIUM CHLORID IN ANIMALS. 



Chlorine, in the form of sodium chlorid, plays an important role in 

 animals, the formation of normal gastric juice being impossible in its 

 absence. An idea of its great importance for the blood may be inferred 

 from the fact that on an average about one-half of the blood ash con- 

 sists of chlorid of sodium. Nearly one-third of the ash of the white of 

 hens' eggs is made up of it. This salt can not be replaced by potassium 

 chlorid, as the latter in the same quantity would exert a noxious 

 influence on the animal. Generally, sodium salts exert an injurious 

 effect on animals only when present in about five times larger quantities 

 than potassium salts. 



PHYSIOLOGICAL OCCURRENCE OF CALCIUM FLUORID. 



The general occurrence of calcium iiuorid in the teeth of animals 

 renders very probable the supposition that it is present in many plants 

 also, and indeed traces have been discovered in several cases. Flu- 

 orids, however, are not necessary for plants, the latter having been 

 raised in culture solutions containing no trace of such compounds. It 

 may be said that soluble fluorids in moderate amounts exert a poison- 

 ous action upon plants, as well as upon animals, and that they are more 

 injurious to bacteria than to yeast — a fact of which practical use has 

 been made in the manufacture of alcohol. 



BEHAVIOR OF PLANTS TO POTASSIUM BROMID. 



Bromine compounds occur normally in seaweeds, but as yet it is not 

 known whether they are present in them only as organic or also as 

 inorganic combinations. The physiological substitution of potassium 

 bromid for potassium chlorid in the higher plants is impossible. In the 

 case of buckwheat plants cultivated with potassium bromid, the writer 

 observed that only one of six lived to bear a single seed, the others 

 dying at or near the flowering stage; heuce the recent assertion that 

 bromids are not noxious for Phanerogams can be admitted only in the 

 case of certain plants or a limited period of development. 



RELATIONS OF ORGANISMS TO IODINE COMPOUNDS. 



Since the discovery that an iodine compound occurs in the thyroid 

 and the thymus glands of animals, it must inevitably be assumed that 

 traces of iodine compounds must exist in soils and plants also. Gautier ^ 

 has demonstrated that there are traces of iodine in the air of Paris. 



' According to Gautier (1899), marine algic contain in 100 grams dry matter 60 

 mgr, iodine, while fresh-water algae contain only 0.25 to 2.40 mgr. 



