25 



reached ' iu the former case but not in the latter. With rubidium 

 chlorid })athologic phenomena made their appearance chiefly after the 

 flowering stage, but with sodium chlorid starvation phenomena were 

 observed very much earlier. 



Molisch had demonstrated that algiie can not develop if the potas- 

 sium salts of the culture solution are reidaced by rubidium salts.- In 

 animals, also, neither ciesium nor rubidium salts can take the place of 

 potassium salts, although a moderate amount of the rubidium salts is 

 not noxious, and in large quantities they are even less injurious than 

 the potassium salts.'' 



NECESSITY OF SODIUM SALTS FOR ANIMALS. 



The great amount of sodium chlorid in the blood has already been 

 mentioned, but the blood contains still other sodium salts of impor- 

 tance, such as sodium bicarbonate (in the ash of ox blood was found 

 14 to 18 per cent sodiunj carbonate) and the secondary sodium phos- 

 l)hate. Both these salts have an important bearing on the respiration 

 process, as they carry in solution to the lungs for exhalation the car- 

 bonic acid j)roduced by even the most remote cells of the body. 



BEHAVIOR OF FUNGI TOWARD RUBIDIUM SALTS. 



It has long been observed that mold fungi thrive in the presence of 

 even very small quantities of potassium salts, traces of which are 

 sometimes contained as impurities iu certain organic comi)ounds. 

 Tliese traces have to be considered in preparing culture solutions for 

 special purposes. Yeast requires a larger amount of potassium, espe- 

 cially in the form of the primary and secondary phosphate, than do 

 mold fungi. Certain kinds of microbes, such as Anthrax bacilli, do not 

 develop well when the amount of potassium salts is very small. Sodium 

 salts can not rei)lace potassium salts even for these simple organisms, 

 but rubidium salts can do so iu certain cases, as iu Bacillus coli, less 

 successfully in B. pyocyaneiis,* and still less in Cladothrix.^ The writer 

 has also established the fact that a mold fungus {PeniciUium) and yeast 

 can utilize rubidium and caesium salts when the composition of the 

 nourishing solution is otherwise very favorable aud contains sugar and 

 peptone. Giluther's observation that the behavior of difterent mold 

 fungi to rubidium salts varies, is interesting, these salts being utilized 

 by Botrytis cinerea, but not by Bhizopus nigricans.^ The less favorable 



' It would be of considerable interest to investigate whether the buckwheat egg 

 cell is properly fecundated when rubidium chlorid iu place of potassium chlorid is 

 offered. 



-On the other hand no injurious influence upon algae is noticed when to the com- 

 plete culture solutions 0.3 per mille of the chiorids of rubidium or caesium is added. 



■^According to Richet, the lethal minimum dose of rubidium in form of rubidium 

 chlorid is 1 gram for 1 kilo body weight when applied subcutaneously. This is 

 about twice as much as the lethal dose of potassium chlorid. 



•»Bot. Centralbl., 1898, No. 26. 



^ Winogradzki has shown that Mycoderma vini also can utilize rubidium salts to 

 advantage, but not caesium salts. 



^ Dissertation, Erlangen, 1897. 



