808 
mined by phosphate- and acetate-mixtures, we found at py = 6.00 
an optimal reaction to the action of the enzyme. On either side the 
action decreases, first slowly, afterwards rapidly. Even at py = 4.5 
and 7.5 it is stopped almost completely. At these py’s injury to 
the enzyme is out of the question during the whole time of the test. 
The place of the optimal py does not change even when the digestion- 
time is five times the ordinary duration. The influence of citrate- 
mixtures is much more inhibitory than that of phosphate- and acetate- 
mixtures. The inhibition is energetic especially on the side of the 
minor py’s. This accounts for the fact that in citrate-mixtures the 
optimal reaction has shifted towards the neutral point. 
Astronomy. — “On absorption of gravitation and the moon's 
longitude.” By Prof. Dr. W. pe Srrrer. Part I. 
(Communicated in the meeting of November 30, 1912). 
By absorption of gravitation we mean the hypothesis that the 
mutual gravitational attraction of two bodies is diminished when a 
third body is traversed by the ine joining the first two. If this 
absorption exists, it will manifest itself by diminishing the attraction 
of the sun upon the moon during a lunar eclipse. Therefore, in order 
to test the reality of our hypothesis, we must compute the pertur- 
bations in the longitude of the moon which are a consequence of 
this decrease of attraction, and compare these computed perturbations 
with the well known deviations of the observed longitude from that 
derived in accordance with the rigorous law of Newron. Nrwcoms, 
in the last paper from his hand (M. N. Jan. 1909) has put before 
the scientific world the great problem of these deviations or “fluctu- 
ations” in the moon’s longitude. They can be represented by a 
term of long period, for which Nerwcoms finds an amplitude of 
12".95 and a period of 275 years (great fluctuation), upon which 
are superposed irregular deviations (minor fluctuations), which amount 
to not more than + 4" in NewcoMmB’s representation. Mr. I. E. Ross, 
Nrwcomp’s assistant, has afterwards represented these minor fluctuations 
by two empirical terms having periods of 57 and 23 years and 
amplitudes of 2.9 and O".8 respectively (M. N. Nov. 1911). The 
outstanding residuals are very small: after 1850 they seldom reach 1". 
In the years before 1850 the minor fluctuations are not so well 
marked, probably because (owing ‘to the smaller number and greater 
uncertainty of the available observations) too many years have 
been combined in each mean result. 
