INDEX 81 



sating, in Amoeba, 11; pulsating, in White-fish, 21. 



Paramecium, 15. Woodchuck, 69. 



Vasa efferentia, of frog, 37. Woodpecker, 69. 



Vegetative pole, 42. Wool, cellular structure of, 12. 

 Ventral blood vessel, of earthworm, 28, 



29. Yolk, of egg, 10. 



Ventricle, of heart of frog tadpole, 44. Yolk plug, of frog gastrula, 43. 

 Vertebrae, 59, 60; centrum of, 60. 



Visceral mass, 63. Zoogeography, 67. 



Viviparous, 38, 39. Zoothamnium, 23. 



Volvox, 24, 25. Zygapophyses, 60. 



