ASTRONOMY: F. H. SEARES 
2\7 
The only plus value comes between the first two periods and the lowest 
values are between the 8-10 and the 10-1 2 J day periods. 
An examination of these values and a comparison with the facts of 
histogenesis shows that acceleration of rate is a plus quantity only dur- 
ing the period before active differentiation of the cells has begun. The 
retarding effect is evident with the beginning of apparent tissue differ- 
entiation and by the ninth to eleventh days the negative acceleration 
is at its height. 
The percentage increments for the six periods represented are re- 
spectively 106, 28, 12, 5, 0 and 0 (fig. 5). There is a very rapid decrease 
at first and then a slower and slower one as zero is approached. The 
data agree with those of ordinary growth. 
First regenerations of frog tadpoles gave results which were essen- 
tially similar to those for second regenerations. 
The data will appear in full in the University of Illinois Biological 
Monographs. 
PRELIMINARY NOTE ON THE DISTRIBUTION OF STARS WITH 
RESPECT TO THE GALACTIC PLANE 
By Frederick H. Seares 
MOUNT WILSON SOLAR OBSERVATORY, CARNEGIE INSTITUTION OF WASHINGTON 
Communicated by G. S. Hale, February 9, 1917 
A significant feature of the distribution of stars over the face of the 
sky is their concentration toward the plane of the Galaxy. Approach- 
ing the Milky Way from either side, we find that objects of all degrees 
of brightness become more and more numerous; with decreasing galac- 
tic latitude, the star-density regularly increases and attains a maxi- 
mum in the star clouds of the Milky Way itself, a fact long known and, 
as early as 1750, the basis of cosmological speculation by Thomas Wright 
of Durham.^ The phenomenon was studied by both the Herschels, 
and more recently Seeliger, Celoria, Pickering, Kapteyn,^ and Chap- 
man and Melotte,^ among others, have given values of the stellar den- 
sity; and yet, from a numerical standpoint, the matter remains even 
now more or less an open question. 
Our knowledge of stellar distribution must include the total num- 
ber of stars per unit area at each galactic latitude, and, as well, of the 
number for each interval of magnitude from the brightest to the faint- 
est; moreover, the magnitudes themselves must be homogeneous and 
in accordance with a uniform scale. The Herschel counts, giving only 
totals to a certain limit near the 14th magnitude, do not satisfy these 
