INTRODUCTION. 27 



withdrawal of their tentacula within their testaceous cove- 

 ring. What a contrast do the simple motions of these 

 animals present to the complicated motor machinery of the 

 human frame ! How immense the chasm of separation 

 between these creatures and man ! 



The laws of phenomena really constitute science, and 

 facts ought ever to be made subservient to their discovery. 

 The zoologists and botanists who devote all their time and 

 attention to the mere business of collecting species, of de- 

 fining their external characters, and of forming systematic 

 arrangements of them, undoubtedly perform a great and 

 valuable service ; but this after all, is but a coarse outline 

 of the natural history of any country. It is not sufficient 

 to obtain specimens of natural history for the cabinet, to 

 group plants and animals according to their outward 

 appearance ; we must look more deeply into the mysteries 

 of their organization, we must study their physiology and 

 the laws of their development. It is true that little pro- 

 gress can be made in these investigations without we avail 

 ourselves of the labors of the systematist ; but after all, the 

 technical description of the external organs of plants and 

 animals, is only the infancy of science. It is not sufficient 

 that we make ourselves acquainted with facts we must 

 study their philosophy. 



For example, it is well known to botanists that the calyx 

 of the bloodroot (Sanguinaria Canadensis,) drops from the 

 flower stem as soon as the petals open and expand, whilst in 

 the blackberry (Rubus villosus;,) it survives the decay and 

 removal of the other parts. Why do the cells of the calyx 

 perish at so early period in the one instance, and remain 

 persistent about the fruit in the other ? What is it that pro- 

 duces their early decay or the prolongation of their vitality ? 

 This is a very simple question, and yet in the present state 



