99 
Also the tangent in .V at the 9*, which passes through N, must 
be counted for two rays of [4]; consequently the order too is equal 
to sir. 
This may also be proved:as follows. The pairs of points 1’, U’ 
of the curve T° are projected out of a straight line / by a pencil of 
planes in involutorial correspondence (6,6), in which the plane (/7’) 
“represents a sextuple coincidence. As the remaining coincidences 
arise on account of the coincidence of U’ with U, 7’ bears sir 
tangents of curves o°. 
Cis evidently a singular point of order one for the congruence 
[¢]; the tangent plane in Cat ®° is the singular plane belonging 
to it. The planes of the six conics 97; are singular planes of order 
two. The six straight lines 6 are double rays. 
5. Analogous considerations hold for pencils (e°) on a nodal cubic 
surface. The representation is then simply brought about by central 
projection out of the conical point. The curves 9? now have one of 
the six straight lines a(6) passing through the conical point and four 
straight lines c as chords, or they pass through the conical point 
and have three straight lines « and three straight lines ¢ as chords. 
Physiology. — “A new group of antagonizing atoms.” I. By 
T. P. Feenstra. (Communicated by Prof. Dr. H. ZWAARDEMAKER). 
i 
(Communicated in the meeting of April 28, 1916). 
It is a matter of common knowledge that a sodium chloride 
solution in the concentration of RINGER’s mixture arrests the action 
of the heart some time after the circulating fluid has been administered, 
and also that contraction can be restored by the addition of potas- 
sium chloride and by calcium chloride. 
These two salts remove the toxic effect of sodium chloride.') A 
normal action of the heart is obtained only if the three salts together 
with sodium bicarbonate are present in the circulating fluid in a 
definite concentration as in bloodserum. Augmentation or diminution 
of the amount of one of the constituents of the fluid induces an 
abnormal action of the heart, which will slow down to a standstill, 
when the difference becomes too great. The relative apportionments 
of the three salts must, therefore, be definite and fairly constant. 
!) Journal of Physiol. Vol. III p. 380, Vol. [V pp. 29 and 222, Vol. V p. 247. 
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