48 GEORGINA B. SPOONER 



EXPLANATION OF FIGURES 



6 Cyclops fimbriatus — egg showing the second pohxr spindle lying near the 

 periphery of the egg in a ball of protoplasm. 



7 Cyclops fimbriatus — first cleavage spindle just forming, showing asters 

 and astral rays. 



8 Cyclops fimbriatus — egg sac after centrifuging, showing three layers, of yolk, 

 protoplasm and oil. 



9 Arbaciapunctulata — egg in india ink solution. The micropyle is not directly 

 opposite the micromeres. 



10 Cyclops fimbriatus — egg sac centrifuged after first cleavage, showing that 

 the layers may bear any relation to the first cleavage. 



11 Arbacia punctulata — section of an egg centrifuged just before the first 

 cleavage, showing the spindle parallel to the stratification. 



12 Arbacia punctulata — section of an egg centrifuged before fertilization- 

 The spindle has formed in the short axis of the protoplasmic layers, perpendicu- 

 lar to the stratification. 



