THE AXIS OF THE EMBRYO. 



145 



embryos, tJiree show coincidence of the axis of the embryo with 

 the first cleavage plane. There is no case of exact coincidence 

 with the second cleavage plane. Fourteen of the embryos have 

 the head directed towards the right of the first line of cleavage, 

 the axis of the body being at an angle with the first cleavage 

 plane of from 30° to 70°. In the remaining six the head was to 

 the left of the first cleavage plane, the angle varying as before. 

 In the experiments of '96 the main purpose in view was to 

 settle the question of rotation of the Q.gg within its membrane 



Fig. III. 



and to find out, if possible, whether gravity had anything to 

 do with the position of the blastodisk. The eggs attached to 

 pieces of glass were fertilized and the glass plates placed in 

 various positions, so that the axis of the Qgg in different cases 

 was vertical, horizontal, and inclined at various angles. 



It was observed that the small oil globules within the &g^ 

 were always found uppermost in whatever position the ^%^ was 

 placed, in one case being directly under the blastodisk at the 

 animal pole, and again directly underneath the adhesive disk at 



