BROMIN AND IODIN COMPOUNDS. 27 



organs: Horsford, in the brain of men; Tammann [1888], in the brain 

 of the calf, in milk and blood, and in egg albumen (about 1 mgr. fluorin 

 in 100 parts of these objects). Jodlbauer observed fluorin compounds 

 also in embryos. Hence the general presence of fluorin compounds 

 in plants must be inferred. The plants probably absorb it from par- 

 ticles of apatite, a fluorin mineral of wide occurrence. 



Sodium fluorid exerts a highly poisonous action on animals and 

 plants; 0.15 gram per kilo body weight of an animal forms the lethal 

 dose and Phanerogams are killed b}^ a 0.1 per mille solution. Algae, 

 yeast, and bacteria are also very sensitive toward it. Still more poi- 

 sonous is the siliconuorid of sodium. 



In exceedingly high dilution, however, fluorids act as stimulants to 

 fungi (Ono), as well as on phanerogams (Aso). Solutions of 0.001 per 

 mille or 150-500 grams per hectare show a very marked stimulant 

 effect on agricultural crops. 



BEHAVIOR OF PLANTS TO POTASSIUM BROMID. 



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

 known whether they are present 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 long ago that only one of six lived to bear a single seed, 

 the others dying at or near the flowering stage; hence the recent asser- 

 tion that bromids are not noxious for phanerogams can be admitted 

 only in the case of certain plants or for a limited period of develop- 

 ment. 



RELATIONS OF ORGANISMS TO IODIN COMPOUNDS. 



Since the discovery that an iodin compound occurs in the thyroid 

 and the thymus glands and also in the blood of animals, it must inev- 

 itably be assumed that traces of iodin compounds must exist in soils 

 and plants also. Gautier" has demonstrated that there are traces of 

 iodin in the air of Paris. He determined also the amount of iodin 

 in sea water to be 2.32 mgr. per liter. Various marine organisms 

 contain moderately large quantities of iodin. For instance, Harnack 

 isolated iodospongin containing on an average 8.2 per cent iodin from 

 marine sponges. Drechsel 6 found in a protein, viz, the axial horny 

 skeleton of the coral Gorgonia cavolinii, 7.7 per cent iodin. On 

 decomposition with baryta this protein yields a compound of the com- 

 position of monoiod-amido-butyric acid. 



a According to Gautier (1899), rnarine algse contain in 100 grams dry matter 60 

 mgr. iodin, while fresh-water algre contain only 0.25 to 2.40 mgr. Dafert and Halla 

 recently discovered iodin in Chile saltpeter. The iodin content of phosphorite also 

 is of some interest. 



&Zeitschr. f. Biologie, 1895, Vol. XV. Drechsel calls this protein "gorgonin." On 

 decomposition it yielded not only iodin, but also 2 per cent chlorin (or bromin?). 



