Nomzelae PEGGlOFr AMIA AND: TS GEEAVAGE. 345 
not only for inverted eggs, but for eggs placed in any position 
whatsoever. It seems to follow that gravity can have no 
directing influence on the cleavage. 
In order to ascertain whether there is any constant relation 
of the embryonic axis to either of the first two cleavage planes, 
eggs were fixed in given positions by weighting, as before men- 
tioned, and a sketch of the early grooves was carefully made in 
each case. These grooves are easily identified for a long time 
in the lower hemisphere of the egg, even as late, in some cases, 
as the early stages of gastrulation. As the sketches made at 
successive intervals showed no movement of the egg during all 
this time, it seems probable that the position of the egg 
remained practically unchanged up to the time when the 
median plane of the embryo was ascertainable. In some cases 
accidental markings on the surface of the egg remained in a 
fixed position until the embryo was well defined. 
Our observations were made on three sets of eggs. The 
results are tabulated below and illustrated by the diagrams 
shown in Cut 20. 
First Series. — At 8 a.m. May 12, 1895, ten eggs in which 
the first grooves had just appeared were fixed in position and 
sketches made at successive intervals. Two of the eggs died 
during gastrulation, leaving eight in which the embryos were ~ 
apparently normal. The results were as follows : 
Eco. EMBRYO VISIBLE. ANGLE WITH First Groove. 
I 6 A.M. May 15 67° 
2 6 A.M. ‘ 0° 
3 5 A.M. ‘s 7iSe 
4 Died during gastrulation 
5 5 A.M. May 15 75a 
6 5 A.M. es 0° 
7 PAC IM ise ine ce 45° 
8 Died during gastrulation 
9 5 A.M. May 15 B09 
10 6 A.M. ‘e om 
Second Series. — At 9 A.M. on the same day, a second lot of 
ten eggs in which the second grooves were well under way were 
fixed in position. Nine of these formed normal embryos. 
