A. C. REDFIELD AND E. M. BRIGHT 35 



stant while the radius of curvature, R, was varied by placing the 

 eggs at different positions on the glass plate. In the other the mag- 

 netic field was varied by altering the current flowing through the 

 solenoid, while the radius of curvature was kept constant by placing 

 each lot of eggs in the same position on the glass plate. 



In the former procedure eggs were spread uniformly over the plate 

 in a thin film of sea water and radiated for 1 or 2 hours in the presence 

 of a strong magnetic field.'' Slender filaments of glass cemented 

 across the plate divided it into chambers, each at a measured distance 

 from A , and prevented the eggs from moving from the position which 



Fig. 2. Photograph of the course of the ;8-rays when undeflected, A, and de- 

 flected, B, by a magnetic field of about 450 gauss. The upper picture was made 

 by placing the photographic plate against the end of the lead blocks which define 

 the beam, so that it was struck a glancing blow by the rays. The lower picture 

 was made by placing the photographic plate under the lead blocks in the position 

 occupied by the glass plate which supported the eggs. 



they occupied while being radiated. At the completion of the period 

 of radiation the plate was removed from the apparatus and the eggs 

 were fertihzed by blowing a shower of sperm suspended in sea water 

 upon them with an atomizer. This procedure was essential in order 

 to prevent eggs being washed from one compartment on the plate 

 to another. About 40 minutes after fertihzation, a cover-glass was 

 laid across the glass filaments, which protected the eggs from being 

 crushed, and measurements of the thickness of the membranes of 



^ Preliminary experiments established the fact that exposure to the magnetic 

 field alone had no effect upon the membrane of the Nereis eggs. 



