95 



exi)eriments of Roux and of Kathariner were insufficient, since the 

 eggs \Yere not quickly enough placed on the rotating machine, and that 

 gravity had had an opportunity to act before the experiments began. Later 

 Morgan ('02) demonstrated for the toad's egg, and Kathariner ('02) 

 for the frog's egg, that if the eggs were rotated from the moment 

 that they were fertilized and kept in continuous motion a normal embryo 

 may develop. Moszkowski has recently ('03) objected to these results 

 on the ground that a centrifugal force replaced the action of gravity, 

 and caused the protoplasm to become arranged as in the normal egg 

 under the constant action of gravity. That this did not, in reality, 

 occur in my experiments was made clear, I believe, in my former 

 paper, in which I stated that the rotation of the eggs was extremely 

 irregular, and not in one plane, as must occur if gravity is to produce 

 the postulated effect. During the present spring I have undertaken 

 a new series of experiments in which especial care was taken to ex- 

 clude the constant action of the centrifugal force during the rotation 

 of the eggs. 



Method. 



A water-motor furnished the power. A bicycle was turned upside 

 down; the rubber tire removed from the front wheel, and a string, 

 running from the wheel of the motor around the rim of the bicycle- 

 wheel, caused the latter slowly to rotate. The wheel made from twelve to 

 sixteen revolutions per minute. The eggs were put into large test-tubes, 

 closed at one end with a cork. These tubes were fastened between 

 the spokes of the bicycle-wheel. Their inner ends were about 5 cm 

 from the axis and their outer ends about 24 cm. The tubes were 

 nearly filled with water, but a large bubble of air was left at the top. 

 As the tubes revolved the bubble of air would pass from one end of 

 the tube to the other end, causing the water and the eggs to swirl 

 twice during each revolution. Inside each tube there had been placed 

 a spiral (of four or five turns) of wire covered with cloth and soaked 

 in paraffine. This spiral, inside the tube, helped to make the motion 

 of the eggs very irregular. 



The eggs were taken from the uterus of the toad, cut into short 

 strings — which rolled up also into short spirals when they absorbed 

 water — and dropped into a dish of water containing sperm. This water 

 was kept in constant motion for ten minutes, so that the strings of 

 eggs were constantly turning over and over very irregularly. The 

 eggs were then placed on the wheel. 



It could be clearly seen that during the revolution the movement 



