998 
of the ontogenetic development of these structures laid down here, 
entirely right and founded on facts. 
A direct continuity between myofibrillae and tendon fibrillae in the 
sense of Scuvrrzm does not exist. 
Leiden, December 1914. 
Physics. — “On the field of a single centre in Kinsruiy’s theory of 
gravitation” By J. Droste. (Communicated by Prof. H. A. 
LORENTZ). 
(Communicated in the meeting of December 30, 1914). 
1. The equations which determine the field of gravitation in 
EINSTEIN and GrossmMann’s theory *), are not linear, hence the field 
: ol (2) oo 
corresponding to the tensor ee eg (o‚v = 1, 2, 3, 4) is not the sum 
3 > : (1 (2 . 
of the fields corresponding to the tensors 20) and 25). The equations, 
indeed, present a certain homogeneity ; when all the g’s are multiplied 
by the constant factor 2 and the 2’s also, then the equations 
y | 
Eme in Oe oe 
= Dr a 5 Ee Yes p gr 12 ar) A 
bd Ce HIP wg 
and 
0 04 ay ~ 
Py Gn (v= Yada. 5e) == % (22 + to») (op = 1, 2, 3, 4) 7 (2) 
„an Ox ap 
remain valid, if they were so before the multiplication. But yet it 
follows by no means from this that a field would be possible, whose 
gs and Vs would be the 4-foild of a given field. Rather the contrary 
may be said to be the case, and this finds its cause in the accessory 
condition that for infinitely increasing distance to the places where 
SE, differs from zero, g,,, Jas, and g,, must converge towards —1, 
g,, towards c’. 
These remarks suffice to make us see that the calculation of fields 
of gravitation is incomparably more difficult in the new theory than in 
the old. (Newron’s theory). In the latter the field may be found by 
an integration; in the former theory this is impossible as appears 
from the above. Now equations (2) are, however, intended to pass 
1) [. Entwurf einer verallgemeinerten Relativitätstheorie und einer Theorie der 
Gravitation, Leipzig bij B. G. Teusner. This treatise has been reprinted in ‘Zeit- 
schrift fiir Mathematik und Physik’, Vol. 62. 
Il. Kovarianzeigenschaften der Feldgleichungen der auf die verallgemeinerte 
Relativitätstheorie gegründeter Gravitationstheorie. Zeitschr, fiir Math. u. Phys., Vol. 63, 
