364 LECTURE XVI. 



bles, and yet living where there is no salt supply? Such people prepare 

 a salt of their own. Thus, Bunge 1 was able to procure a salt obtained by 

 ignition of a plant which was used by the negroes in the southern part of 

 Khartum, Africa, as a seasoning for their vegetable food. The analysis 

 of this salt showed it to contain 19.27 per cent Na 2 and 4.92 percent 

 K 2 O, or nearly six equivalents of soda to one of potash. It is interesting 

 here to find that the natives have selected a plant (Salsola, or salt-wort) 

 which is especially characterized by its high soda content. The natural 

 instinct, however, does not always assert itself so well in this direction, 

 for there are other races' which use for salt the ash of a plant rich in potash. 

 Lapicque 2 examined such a salt. The inhabitants of the Angoni district 

 in British Central Africa use a substance prepared by burning goat manure 

 and wood. Analysis showed that it contained 21.98 per cent KC1 and 

 . 47 per cent NaCl. 3 It is interesting to learn, however, that after Lapicque 

 had shown the natives how to obtain common salt, they gave up the prepa- 

 ration of their own native condiment. Salt, for the inhabitants of Angoni, 

 is an extremely expensive article of commerce. The natives toil for salt 

 upon the plantations. 



The assumption that the high potash content of vegetable foods causes 

 losses in the sodium content of the blood and indirectly of the tissues, is 

 not in agreement with certain observations. Thus, Landsteiner 4 fed a 

 number of young rabbits exclusively upon meadow hay for 3^ months. 

 At the same time another lot of similar animals was fed entirely with 

 cow's milk, which contains for one equivalent of soda only 0.7 to 3.7 

 equivalents of potash. Now although these two series of animals were 

 fed with nourishment containing quite different relative amounts of alkali, 

 nevertheless, at the end of the experiment the soda and potash content of 

 the blood was the same in each case. We know, furthermore, that in 

 spite of the fact that rabbits and hares live on fodder rich in potash, they 

 do not show the slightest craving after salt, and under normal conditions 

 do not obtain any in addition to what their food contains. It is possible 

 that the organism of these animals may be different in some way, so that 

 the loss of sodium is avoided. On the other hand, it is a well-known fact 

 that purely herbivorous animals, such as cows and sheep, can subsist upon 

 fodder rich in potash for a long time without any extra salt, and there is 

 no recognizable disturbance in the development of these animals. It is 

 indeed possible, and even probable, that the potassium salts contained in 

 the fodder do not have such a marked effect as pure potassium chloride, 

 when taken by itself into the system at one time and absorbed as such. 



1 Z. Biol. 41, 484 (1901). 

 3 L'Anthropologie (1896). 



3 Abderhalden: Pfliiger's Arch. 97, 103 (1903). 



4 Z. physiol. Chem. 16, 13 (1892). 



