( 71 ) 



each other that they have in projection a hexagon in common ^). 

 The limiting polygon is a regular decagon with side (/. The figure 

 is central symmetric as is the ])olytope itself. The vertices appear in 

 three wreaths of ten regular decagons. 



5. Though we have tinished what we had proposed to ourselves 

 to do, the plate still contains another diagram. In tig. Ji) we have 

 constructed accurately the radii of the circumcircles of the different 

 projections and — for the cases where the limit ijig polygon is a 

 semiregular decagon — also the side of the i-egular pentagon inscribed 

 in the circumcircle. So the labour of the pure construction of the 

 figures is reduced to a minimum. This diagram will be clear if we 

 remark that OA is divided in extreme and mean ratio, that on 

 OB measured from are to he found the radii of the circum- 

 circles and on OC parallel to AD measured likewise from the 

 sides of the regular pentagons inscribed in the circumcircles of the 

 semiregular decagons. Moreover we have OE^F(r=z, OF=EG=(l, 

 whilst in connection with 16 



OB = QS, 01 =Q T, OK = FT 

 and the points e^ , e^e^ , e^e^ on OB are obtained by letting down 

 the perpendiculars from H, I, K on OB. Finally Ee^ , Fce^e., and 

 Ge^e^es are parallel to AD. 



Groningen, March 10, 19TJ. 



Physiology. — "On the irritation-effect in living Organisms." By 

 Mr. J. L. Hoorweg. (Communicated by Prof. H. Zwaakdemakkr). 



(Communicated in the meeting of April 28, 1911). 



1. In this paper I wish to make a few remarks with regard to 

 an essay of Hill (1) intending to give an extension to Nernst's (2) 

 theory about the electric irritation of living organisms. 



I may remind niy readers of the fact that ever since the year 

 1890 1 have occupied myself with this subject, when I communi- 

 cated in the Ned. Tijdschrift voor Geneeskunde {^) experiments about 

 the contraction of the human muscles by condensator-discharges, and 

 indicated in this paper a simple connection between the capacity 6' 

 of the condensator used and the potential F, to which the latter 

 was to be charged in order to produce a minimal response. This con- 

 nection is expressed by the formula 



1) We remember that under ej the difference in orientation was 72°. 



