INTRODUCTORY 



. y 



B 



FIG. 2. 



A, Large spherical egg (female gamete) of Bladder Wrack (Fucus), surrounded 

 by many small motile spermatozoids (male gametes). (After Thuret. x 330.) 



B, Human gametes highly magnified : egg to the right, spermatozoon to the 

 left. The egg is enclosed in a transparent envelope which disappears during 

 development. Each division of the scale represents .05 mm., or about .-,,',,, inch. 



