I7 2 RALPH S. LILLIE. 



and other cells during mitotic division, and that the astral 

 rays are in part an expression of this flow, the central "sphere" 

 representing an accumulation of the more fluid part of the 

 protoplasm. Chambers brings evidence from micro-dissection 

 favoring the view that the sphere is formed by the confluence 

 of a system of radiating channels containing a more fluid "hyalo- 

 plasm" separated by radiating protoplasmic tracts of a solid or 

 gel-like consistency. If the general surface of the dividing cell 

 outside the equatorial area is electrically negative (in the usual 

 physiological sense) relatively to this latter area, as the character 

 of the form-change and certain other facts indicate, 1 then the 

 positive stream in the cell-circuit must enter the surface at the 

 polar and circumpolar areas and leave at the equatorial area. 

 The conditions for a centripetal flow of fluid from the polar areas, 

 due to electrical endosmose, would thus be furnished. The 

 relation of such a flow to the general form-characters of the 

 mitotic figure should be reconsidered in the light of these possi- 

 bilities. 



IV. THE POSSIBILITY OF ELECTROLYSIS AT THE SEMIPERMEABLE 



CELL-BOUNDARIES. 



Throughout the foregoing comparison between electrolytic 

 precipitation-growths and organic growths it has been assumed 

 that the formation of electrical circuits between different regions 

 of the cell-surface, and associated with processes of the nature of 

 electrolysis, is possible; and that the conditions under which 

 such circuits arise are of the same essential nature as those deter- 

 mining the formation of local circuits between different parts of 

 a metallic surface. This assumption may not appear at first 

 sight to be consistent with our knowledge of the general conditions 

 under which circuits are formed by chemical action, and elec- 

 trolysis takes place. In the kind of process considered as typical 

 by electrochemists, a part of the circuit always consists of a 

 metallic conductor; this connects the two ion-forming or ion- 

 combining surfaces (electrodes), which are in contact with the 

 electrolyte-solution. In the living cell it is obvious that no 

 conductor of the first class is present. In other respects, how- 



1 Cf. R. S. Lillie, Journ. Exper. Zoo/., 1916, Vol. 21, p. 369. 



