149 



The Structure of Protoplasm 



Fig. 6. Recession of the cleavage furrows as a result of hydrostatic compres- 

 sion. A, eggs (Arhacia puiictulata) 10 seconds after a pressure of 6,500 lbs. /in.' 

 was established in the chamber; B, two minutes later, pressure still maintained; 

 C, two minutes after decompression, which occurred immediately after photo- 

 graph B was taken. Note (bl and b2) that recession of the furrow occurred 

 even though the "blastomeres" were conne^ed by a mere strand of protoplasm 

 at the time when the pressure was applied. The fertilization membranes were 

 removed shortly after the spei'm was added. 



pressures merely retard the rate at which the furrow intrudes upon 

 the division axis, and a quantitative study of this effect was under- 

 taken. 



In these experiments the fertihzed eggs were allowed to develop 

 in the chamber at atmospheric pressure until 4 minutes before the 



