Literarisch-kritische Rundschau. 371 



of the mass of the larger body only, in a field of more tban 

 one "heavy body"? Or wbat would be tbe value of a diagram of 

 tbe electrostatic field between two cbarged conductors at opposite 

 ends of a lecture-table covered with apparatus of all kinds, if no 

 account were taken of tbe presence of tbese beterogeneous para- 

 pbernalja, and of tbe lecture-table itself. 



Finally I may betray a weakness of our kind ; and tbat is 

 a panic fear of mathematic expressions, and in particular of tbose 

 tbat contain tbe Symbols "d", "A" & and tbe long "j". Tbe 

 scbool-matbematics tbat most of us bave, alas! forgotten, never 

 reacbed as far as tbe infinitesimal calculus. It was only wlien, 

 witb tbe kind aid of a matbematical friend, I conquered my fears, 

 tbat I was able to ascertain tbe meaning of Dr. Greigel's 

 equations and tbeir bearing on tbe subject; and tbat after all 

 tbe "d's" "A's", & "f s" did not matter. 



I. 

 We bave just noted tbat tbe cell-tield is dicentric, and tbat 

 Geigel's equations only deal witb a force acting about a Single 

 centre. It migbt be tbougbt by tbe uninitiated tbat tbis would 

 vitiate bis equations, and tberefore bis general conclusion. Tbe 

 equation goes, no doubt ; but tbe general conclusion can be sbow^n 

 to bold also for a two-centred field tbat tbe cbromosomes sbould 

 advance, as Geige 1 supposes, witb tbe axial ones in advance, 

 and tbe peripberal ones lagging bebind. Tbis is susceptible 

 of a very simple geometrical demonstration, for forces acting 

 about centres, and obeying tbe Newtonian law : i. e. decreasing in 

 intensity as tbe distance increases. We may suppose tbe space 

 around eitber centre divided up by closed curves into a series 

 of zones sucb tbat tbe attractive force is identical at every point 

 of any given zone; of course tbe force is more intense in any 

 given zone tban on tbe zones outside itj and less tban on tbe 

 zones witbin and nearer tbe centre. Sucb zones we may call 

 zones of equal attractive level, or to use tbe common tecbnical term 

 "equipotential zones". In Figures 1, 2 will be seen tbe distribution 

 of tbe equipotential zones in a field about two centres: wbetber 

 tbey be unlike (Figure 1) or like (Figure 2), in eitber case tbe 

 equator is neutral. It is obvious tbat on any transverse plane at 

 rigbt angles to tbe axis uniting tbe centres, a point nearer the 



