Livingston : Chemical stimulation of a green alga 23 



the partially coagulated groups or masses of colloidal particles. 

 And if, as is probable, the seat of vital activity lies in the colloidal 

 portion of the protoplasm rather than in the permeating aqueous 

 solution, it becomes possible to see how an incipient production 

 of the hydrogel phase in certain regions throughout the proto- 

 plasm may result in the same sort of alterations in permeability 

 and lability as those brought about by general extraction of water 

 with its accompanying increase in density of the vital substance. 

 In brief, the suggestion here put forward is, that toxic ions may 

 virtually bring about an extraction of water from the vital portions 

 of the protoplasmic mass, and that this may result in the same 

 obvious and tangible responses as those caused by direct extrac- 



+ * 



tion of water from the whole mass. Before this suggestion can be 

 taken seriously it will be necessary to know more of the influence 

 of ions upon colloidal solutions. 



Another possibility, closely related to the one just presented, 

 is that the toxic cations may act upon the enzymes of the vital 

 substance in such a manner as to bring about the changes noted. 

 Indeed, the alteration of enzyme action (which appears in these 

 days to have come to mean much the same as vital action, at least 

 to play the leading part in our conception of the latter) may well 

 be the common effect of water extraction and the entrance of poison 

 cations into the living substance. Both suggestions are thus seen 

 to be possible at the same time, the latter becoming a part of the 

 former. The probability of the last idea, can be judged best only 

 after more data have been obtained on the effect of poisons upon 

 enzyme action, which work has happily already begun. * 



*See the following papers on this subject: 



Zoethout, W. D. On the production of contact irritability without the precipita- 

 tion of Ca salts. Am. Jour. Physiol. lo : 324-334. 1904. — Further experiments on the 

 influence of various electrolytes upon the tone of skeletal muscles. Am. Jour, Physiol. 



10: 373-377. 1904- 



Brown, O. H. Effects of certain salts on kidney excretion with especial reference 

 to glycosuria. Am. Jour. Physiol, to : 378-383, I904. 



Neilson, C. H. & Brown, O, H. Effect of ions on decomposition of hydrogen 



peroxide and hydrolysis of butyric ether by watery extracts of pancreas. Am. Jour. 



Physiol. 10 : 335-344- 1904. — Effects of ions on decomposition of hydrogen peroxide 

 by platinum black. Am, Jour. Physiol. 10: 225-228. 1904, 



Neilson, C. H. The hydrolysis and synthesis of fats by platinum black. Am. 

 Jour. Physiol, 10: 19I-200. 1903. 



McGuigan, H. Relation between decomposition tension of salts and their antifer- 

 mentative properties. Am. Jour. Physiol, 10: 444-451. 1904. 



