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TEE POPULAR SCIENCE MONTHLY 



in which the egg undergoes a part of its development within the body of 

 the mother, as it is of oviparous forms in which the eggs are laid before 

 development begins. 



The fertilized egg of a star-fish, or frog, or man is not a different 

 individual from the adults of these forms, rather it is a star-fish, a frog, 

 or a human being in the one-celled stage, and thereafter this new being 



I 8 * Mat. Sp 





1* TB 



&N 



Figs. 6-9. Successive Stages in the Maturation and Fertilization of the 

 entrance cone (EC) and sperm nucleus (JA T ) into the egg. Fig. 6 shows the first ma- 

 formed by this division ; Fig. 8, the second maturation spindle (2d Mat. Sp.) and the 

 in the first cleavage spindle (1st CI. Sp.). (From F. R. Lillie.) 



