10 



phenomeiiou migbt be due, as iu the case of the alga Spirogyra, to 

 slight traces of copper sometimes found iu distilled water and derived 

 from the copper vessels used in distilling. Experiments were there- 

 fore repeated, water distilled from glass vessels being used, but the 

 effect was the same — the infusoria died with bloating, their j^rotoplasm 

 swelling and disintegrating. The only conclusion that can be drawn, 

 therefore, is that the distilled water extracts from them traces of neces- 

 sary constituents, which must be of mineral nature, since common water 

 containing some mineral matter has no such action, but forms the very 

 medium of existence for these organisms. A similar effect could not be 

 observed with the same distilled water on algse cells, which may remain 

 alive in it for a considerable time, although the growth ceases. But 

 here the walls of the cytoplasm are probably of greater density, which 

 would prevent the mineral matters of the cell from passing easily to 

 the outside. 



This phenomenon observed in the case of infusoria strongly resembles 

 that of the red blood corpuscles and leucocytes, which are adapted to the 

 degree of concentration of the serum, and which die when transferred 

 into distilled water, but remain alive for some time in a sodium chlorid 

 solution of O.G per cent. The nature of the mineral salts loosely bound 

 by the proteids of the living matter may vary with the character of 

 these i)roteids. In the one case it may be sodium chlorid, in another 

 the secondary potassium phosphate, and in a third a calcium salt. It 

 should be pointed out once for all that we can hope to understand the 

 living state of protoplasm only when the proteins of the living matter 

 are recognized to be chemically labil bodies, which the slightest influ- 

 ence often suffices to transform into the more stable isomeric forms of 

 dead matter. Relatively stable proteins are also those in milk and 

 the reserve proteins in eggs and seeds. Spontaneous transformations 

 of labil compounds into stable ones by atomic migration often take 

 place very easily, for example, when certain amido aldehydes or amido 

 ketones are liberated from their combination with acids. 



Years ago M. Nencki ' recognized the importance of the mineral mat- 

 ter combined with the plasma proteids. "All proteins ^ occurring in 

 the living organisms are combined with mineral substances, whereby 

 the proteins concerned acquire specific i)roperties and functional sig- 

 nification iu the organisms." 



It may be i^roper here to call attention to another phenomenon, first 

 recognized by Wolff. He determined the minimum of each mineral 

 nutrient necessary for the normal development of the oat plant when 

 the other mineral nutrients were in excess, and found that when all 

 the mineral nutrients are offered in the determined minimum amounts 

 at the same time it is impossible for the plants to fiower and fruit 



'Arch. des. Sci. Biologiquea de St. Petersburg, 1894, Vol. Ill, p. 312. 



^While "protein"' is the general denomination of all kinds of albuminous sub- 

 stances, the word "proteid'" applies especially to the complex proteins, e. g., 

 nucleo-albumin, mucin, hiemoglobiu, etc. 



