ANALYTICAL INDEX. 



311 



CHAPTER VII.— continued. 



§ 6. ASCIDIA PAPILLA, 



History of difficult investigation, 



Scanty knowledge of the creation, 



Ascidia papilla, 



Social and solitary, 



Vitiated medium, 



Propagation, 



Spinulu, 



Lively, active, 



Metamorphoses to an Ascidia, 



Period elapsing in metamorphosis, 



Quiescence essential, 



Plate XXXVII. figs. 1-11, 



PAGE 147 



148 

 149 



ib. 



ib. 



ib. 

 150 



ib. 



ib. 



1 5 1 



152 



ib. 



ib. 



CHAPTER VIII.— Compound Ascidia, 



Design of Nature, simple, . 

 Functions of solitary and social animals, 

 History of compound animals very obscure, 



153 



ib. 

 154 

 ib. 



§ 1. Botryllus verrucosus, Plate XXXVIII. 

 Irregularities of form, 

 Systems, .... 



Specimens liable to decompose, 



1.55 

 ib. 

 ib. 

 156 



§ 2. History of a young specimen, 

 Progressive increment, 

 Circulation, 



Vessels and channels for circulation, 

 Flux and reflux of the fluid, 

 Yellow globules in it, 



156 

 15? 

 ib. 

 158 



ib. 

 ib. 



§ 3. Adult Botryllus, 



Systems composed of ascidia;, 



Perpetuation, 



Reciprocal analogies in early stages, 



Yellow corpuscula in the flesh, 



Ovoidal capsules discharged, 



Active yellow spinuloe from them, 



Evolution of the spinula, 



Head is rivettcd and secured by 8 radicles, 



Metamorphoses in ninety hours to an ascidia, 



159 



16(1 



161 



ib. 

 ib. 

 ib. 

 ib. 



162 

 ib. 



16:; 



