18 THE SIGNS OP LIFE [LECT. 



negative to a resting tissue element ; but whether we call it 

 electro-positive or negative, the active element is " zincative." 



9. " Solution-pressure"- -To those of you who are accus- 

 tomed to think about currents through electrolytes, in terms 

 of ions creeping through a solvent, this matter should present 

 itself in a very simple light. Active protoplasm takes on a 

 higher " solution-pressure " (in the sense with which Nernst 

 has made us familiar), and electro-positive ions migrate in 

 greater abundance from protoplasm to lymph. There is then 

 " current of action," and I do not think that we need at this 

 stage pause to object whether this increased pressure may 

 be not of the protoplasm itself but of paraplasm (? fat, 

 ? carbohydrate) set in motion by protoplasm. Whatever the 

 nature of the ions may be, we must picture them as laden 

 with positive charges, and pressing into the lymph-bath from 

 spots where they have become congregated and accumulated, 

 i.e., in and around the meshvvork of living matter. Imagine 

 simple hydrogen kations, or if you like, more complex 

 hydrogen and carbon kations, as issuing forth from a solid 

 coast to a fluid atmosphere, where their oxidation is con- 

 summated --forming water, lactic acid, and carbon dioxide 

 as their typical end-products. These notions, in my way of 

 thinking, are the physiological connotations involved in the 

 brief statement that "active tissue is zincative" And if you 

 have gone so far, you will almost certainly go one step 

 further, and imagine that just as a zinc rod that has given off 

 zinc ions to its surrounding medium, is for the moment, nega- 

 tively charged, so a core or stem of living stuff, immediately 

 after a discharge of positively charged ions is relatively negative. 

 Current of action is thus followed by an opposite after-current ; 

 du Bois' " negative variation " is followed by Hering's " positive 

 after-variation." But I do not wish to pursue this point in detail 

 now, for there are no experiments in evidence before you. An 

 opportunity of demonstration may perhaps arise at a future 

 lecture. 



5 10. Summary. Will you think of these things? I will 



