262 



ANALYTICAL INDEX. 



CHAPTER IV. — continued. 



Instincts and habits of the hydra, 

 Luxuriant Sertularia interesting, 

 Pith obscures the skeleton, 

 Ascidian, asteroid, hellanthoid hydra. 

 Life of Sertularia dependent on the pith. 

 Entire specimens rare, 

 All originate from a single hydra, 

 Differences, anomalies of young and adults, 



§ 1. Sertularia Polyzonias, 

 Hydra with 24-26 tentacula, 

 Attempts to feed it, . 



Alledged food of zoophytes, 

 Vesicles with 24 spherules, 

 Hydrae from their planulae, 

 Hydrse regenerated, 

 Plate XXII. explained, 



I'AliE 139 



ib. 



ib. 

 140 



ib. 

 141 



ib. 

 142 



143 

 144 



ib. 

 145 

 146 



ib. 

 148 

 149 



§ 2. Sertularia Abietina, 



Every animal product is peculiar. 



Genus — variety. 



Hydra with 24 tentacula, 



Syme's P., Nomenclature of Colours, 



Compound and simple vesicle. 



Shallow vessels for microscopic objects. 



Root of the Sertularia, 



Hydra developes from the pith. 



Lowest flourishes first, 



Hydra survives a month, 



Compound ampullate vesicles, 



Planulse of variable shape. 



Evolution within vesicles in situ is rare, 



Ellis' figures explained. 



Are prolific vesicles permanent ? 



Young hydra; surviving a month, 



Plates XXIII., XXIV., XXV., explained, 



150 



ib. 



ib. 

 151 



ib. 



ib. 

 152 

 158 

 154 



ib. 



ib. 

 155 



ib. 

 156 



ib. 



ib. 



ib. 

 157 



3. Sertularia abietinula. 



Narrow distinction of zoophytes, 

 Hydra with 18 tentacula, 

 Irregular articulations. 

 Vesicles of various shape, 



157 



158 

 ib. 

 ib. 

 159 



