TABLE OF CONTENTS ix 



the use of certain other parts, thus acting unfavourably on their 

 development, reducing them, and finally causing their disappear- 

 ance. 



(See the Additions at the end of Part I.) 



VIII. Of the Natural Order op Animals, and the way 

 in which their classification shoxild be drawn 

 up, so as to be in conformity with the actual 

 Order of Nature - - 128 



That the natural order of animals constitutes a series, which 

 we should traverse from the most imperfect animals to the most 

 perfect, in order to be in harmony with the order of Nature ; for 

 Nature did not bring them all into existence at the same moment. 

 Since she had to form them in turn, she was obUged to begin with 

 the simplest, and only produced at the end those with the most 

 complex organisation. That the classification presented here- 

 with is unquestionably the one that approaches most nearly to 

 the order of Nature ; so that if there are any corrections to be 

 made in it, it can only be in matters of detail ; I believe, for 

 instance, that the Naked Polyps should form the third order of 

 the class, and the Floating Polyps the fourth. 



Additions to the Subject-matter of Chaps. VII. and VTII. 173 



PART II. 



AN ENQUIRY INTO THE PHYSICAL CAUSES OF LIFE, THE CON- 

 DITIONS REQUIRED FOR ITS EXISTENCE, THE EXCITING FORCE 

 OF ITS MOVEMENTS, THE FACULTIES WHICH IT CONFERS ON 

 BODIES POSSESSING IT. AND THE RESULTS OF ITS PRESENCE 

 IN THOSE BODIES. 



Introduction - 183 



Some general considerations on nature, and her power to create 

 life and organisation, and subsequently to increase the complexity 

 of the latter. In all these operations, she works only by the action 

 of various moving fiuids on supple bodies, which are modified, 

 organised, and animated by these fluids. 



I. Comparison of Inorganic Bodies with Living Bodies, 



FOLLOWED BY A PARALLEL BETWEEN AnIMALS 



AND Plants 191 



That there is a great difference between living bodies and inor- 

 ganic bodies. That animals are essentially distinguished from 

 plants by IrritabiUty, which is possessed exclusively by the former, 



I and which enables their parts to make sudden movements, repeated 



I as often as they are stimulated by exciting causes, — a peculiarity 



I' which does not occur in any plant. 



f 



