INDEX AND GLOSSARY 



503 



Vestige, vestigial {vestigium, a trace), 

 applied to any structure which has be- 

 come atrophied or undergone reduction 

 beyond the limits of usefulness, 118 

 Vlb'riO(77(^r<7, to vibrate), 86, 88, (Figure) 

 Visceral {viscus, an internal or^an), ap- 

 plied to the layer of coelomic epithelium, 

 or of peritoneum, covering the intestine 

 and other internal organ'^, 274 

 Visceral ganglion, Mussel, 362 

 Vitelline {vitellus, yolk) membrane, the 



cell-membrane of the ovum, 257 

 VolVOX {toIvo, to roll), 264 (Figures) 

 VORTICELLA (diminutive of vortex, an 

 eddy): — Figure, 127: occurrence and 

 general characters, 126 ; structure, 126 : 

 asexual reproduction, 131 : conjugation, 

 133 : means of dispersal, 132, 134 : encys- 

 tation, spore-formation, development, 

 and metamorphosis, 133 



W 



Waste-products, ^^ 

 Water of organization, 5. 29 

 Whorl of leaves, 205 

 Wood, See Xylem. 

 Work and Waste, 14 



Zylem((vAoi/, wood), the inner portion of 

 a vascular bundle, 417, 450, 463 



Yeast, 71 



Teast-plant. See Saccharomyces. 

 Yellow-cells of Radiolaria, 154 

 Yolk-granules or spheres. 68, 233, 256 



Zoog^oe'a (^woi', an animal : vAot'a, glue), 

 85 



Zooid (^woc, an animal : ctjof, form\ a 

 single individualof a compound organism, 

 I35. 234 



Zootham'nium (^uof, an animal : 6ativo^, 

 a bush) : — Figures, 134, 138 : occurrence 

 and general characters, 135 : dimorphism 

 of zooids, 135 : means of di,spersal, 136 : 

 characters and mutual relations of species, 



„ 137 



Zooxanthell'a (iS>ov, an animal : fav0o«, 

 yellow), 154 



Zyg'ospore (fvyoi', a yoke : <nropa, a seed), 

 applied to a resting zygote formed by the 

 conjugation of similar gametes, 166' 



Zygote (fi/yioTo*, yoked), the products of 

 conjugation of two gametes : — Hetero- 

 mita, 41 : Vorticella, 133 : Mucor, 165 : 

 Vaucheria, 174 : Spirogyra, 198 



THE END 



