Pee eS ee eee ee ee 
1898 ] CURRENT LITERATURE 67 
action of the current is really chemical and molecular (poisoning) action of 
the electropositive ions set free at the anode, which leads to the formation of 
alkalies in that region. In support of this they point out that a certain dura- 
tion of the current is necessary for the production of any reaction, and show 
that the effect of dilute alkalies is precisely the same as the effect of the 
current at the anode. The authors think it probable that all galvanic action 
is indirect in the same sense. 
In the paper on the theory of the physiological action of light and gravity, 
Professor Loeb expresses confidence in the complete analogy between electric 
and photic stimuli; theorizes on the source of energy for geotropic phenom- 
ena; demonstrates clearly (in certain cases at least) the mechanics of stimu- 
lation curves; and discusses the so-called “light sense” of eyeless animals. 
The energy for geotropic curvatures he ascribes to such change of position 
of substances in the cell as increases or decreases the surface for chemical 
reactions. This change is conceived as due to the unequal specific gravity 
of the different substances which become spatially rearranged when the 
organ is displaced. Such rearrangement leads, directly or indirectly, to the 
increase of the chemical reaction surfaces of the materials in the cells on the 
under side of the stem, and their decrease in those on the upper. This theory 
reminds us Strongly, mutatis mutandis, of the oldest explanation of geo- 
tropism. 
As to the mechanics of curvatures, Loeb holds that in all organisms, ani- 
mal or plant, whether growing, locomotive, or attached, there is the same 
variable, viz., contractile protoplasm, whose contraction is brought about by 
stmuli, and that this contraction is the efficient cause of the curvatures. 
This agrees well with observations on the shortening of the cells on the con- 
Cave side of plant organs, and the accumulation of osmotically active sub- 
Stances in the cells of that side.’ Loeb adds a beautiful demonstration from 
Campanularia, a hydroid polyp. 
~In the first of a series of papers on the physiological action of ions, Loeb 
Calls attention to the fact that Kahlenberg and True, who were the first to 
Study this general subject, used as a test organism one which did not permit 
Sufficiently accurate discriminations, Loeb has used muscle, and determined 
the effect of H and HO ions in equivalent solutions upon the increase of the 
muscle in weight when immersed in a physiological salt solution. In general 
it was found that the physiological action of dilute inorganic acids and bases 
was equal when the number of H or HO ions per unit-volume was equal. 
For organic acids this was not true, on account of the anions and undissociated 
The relative poisonousness of ions of the groups Li, Na, K, Rb, 
Cs, and Be, Mg, Ca, Sr, Ba depends on the rate of migration of the ions and 
Rot on the atomic weight of the elements.—C. R. B. 
