34 



THE AMERICAN MUSEUM JOURNAL 



about this is collected the yolk or food material contained in the 

 egg. This axis may be followed throughout the development 

 and has been found to correspond to the dorso-ventral axis of 

 the future larva. 



About the time of the change in the position of the nucleus 

 and protoplasm, a division of the former takes place. One of 

 the portions resulting from this division, surrounded by a small 

 amoimt of protoplasm, is extruded at the animal pole, where it 

 remains for a time as a minute body. This is the "first polar 



MODEL 1, A 



The individual egg showing the clear protoplasmic area above, under the 

 two polar bodies ; the yolk with the yolk globules below. In the protoplasm at 

 the animal pole is seen the egg nucleus. The sperm nucleus is represented 

 shortly after entering the lower half of the egg. 



body" and is the larger of the two adherent bodies shown in 

 Model i,B. 



This process of division of the nucleus is soon repeated, 

 and a second smaller polar body is extruded. These two polar 

 bodies remain in position for a considerable length of time. 

 Although they do not take any part in the future development, 

 becoming ultimately detached and lost, their elimination is of 



