424 



SCIENCE. 



[N. S. Vol. XV. No. 376. 



of the metal; the less tlie former and the 

 greater the latter, the more cations are given 

 oS, and vice versa. The result of the loss is 

 a charging of the metal with negative and of 

 the solution with positive electricity. A second 

 metal introduced into the solution, with a 

 different relation of osmotic pressure and solu- 

 tion pressure, becomes charged positively, and 

 the result is a difference of potential between 

 the two metals. 



In discussing the action of the galvanic cur- 

 rent on protoplasm, the question is raised as 

 to how the well-known effects are brought 

 about. A possible factor is the electrolysis 

 of the medium surrounding the living sub- 

 stance, in which case galvanic stimuli should 

 be regarded as chemical stimuli. Verworn 

 regards this possibility as doubtful, and if 

 it occurs at all, it must be altogether sub- 

 ordinate. Much more important, doubtless, is 

 the direct electrolysis of the living substance 

 itself. A possible factor in the galvanic ac- 

 tion is the movement of the liquids in the 

 porous cell substance. This is suggested by 

 the work of Carlgren, who, by the action of 

 strong galvanic currents on dead cells, was 

 able to obtain phenomena closely analogous 

 to those occurring in living substance. The 

 relative shares taken by these various factors 

 in galvanic action must be decided by future 

 investigation. 



Molisch's work on the death of plants by 

 freezing is noted, the general conclusion being 

 that in such cases death is due to the abstrac- 

 tion of water from the protoplasni and the 

 resulting profound alteration in the chemical 

 structure of the compounds of the protoplasm. 

 Regarding the action of chemical stimuli, the 

 author takes the conservative position that in 

 many cases, but not in all, osmotic action is 

 associated with purely chemical action. The 

 two factors have been only rarely distinguished 

 sufficiently, and in most cases it remains to 

 be decided to what extent the stimulating 

 power of the chemical substance is due to its 

 chemical, and to what extent to its osmotic 

 properties. 



The observations of Weil and Frank, which 

 tend to disprove the hypothesis of the con- 

 tractility of the dendrites of nerve cells, are 



quoted approvingly. So also is the work of 

 Myer and of Overton, who found that the 

 solubility of narcotics in fats and oils is a 

 great factor in their narcotizing power. Nar- 

 cosis is accomplished through the agency of 

 the undivided molecule of the narcotic, not 

 through its decomposition products. Narcosis 

 appears to be a contact effect. 



The author devotes a page to the discussion 

 of the effect of the Roentgen rays on organ- 

 isms, but the facts so far discovered are too 

 few to allow conclusions of value to be 

 drawn. 



In discussing the origin of life the theory 

 of P. J. Allen is added to those heretofore 

 given. This author believes the beginnings of 

 life to date, not as Pfliiger assumes, from the 

 time of the earth's incandescence, but from 

 the period when water first appeared on the 

 earth's surface. The powerful shocks of 

 lightning which miist have occurred contin- 

 ually in the damp, warm atmosphere then ex- 

 isting, led to the production of ammonia and 

 the oxides of nitrogen, as happens to-day. 

 These substances were carried down in solu- 

 tion by the rains, and on the surface of the 

 earth met solutions of carbonic acid and the 

 chlorides, sulphates and phosphates of the 

 aUvalies and metals. Thus the opportunity 

 was given for the most varied nitrogenous 

 combinations, and the first living substance 

 then came into being. 



The chapter on the mechanism of life is not 

 greatly altered. The 'biogen hypothesis,' as 

 the author now terms it, is considered some- 

 what more fully than before, in the light of 

 the work of Detmer, Loew and F. J. Allen, 

 but it is not essentially changed. Attention 

 is called to Jennings's careful work on the 

 mechanism of tactic movements, and to Ehum- 

 bler's interesting physical analyses of cell 

 phenomena. 



In the preface Professor Verworn speaks of 

 the present great activity of investigators in 

 all fields of general physiology, and laments 

 the fact that within the narrow confines of 

 one book so many of the important contribu- 

 tions must be mentioned without discussion or 

 be omitted altogether. Notwithstanding this 

 fact, his book still remains by far the best 



