INTRODUCTION. 23 



in some inferior animal. Hence "the advantage — the 

 necessity, rather — of combining a general knowledge of the 

 organization of the lower animals with that of man, which 

 ought always to claim the first attention of the medical 

 student, is now universally recognized. A great part, of 

 the best part, of the proofs of the most important physio- 

 logical doctrines are derived from comparative anatomy. 

 The increasing taste for the natural sciences, and the rapidly 

 diffusing knowledge of zoology and geology render it scarcely 

 pardonable in a member of a liberal profession to be wholly 

 unversed in them, and almost discreditable to a medical 

 man to be unable to offer any sound opinion on a fossil 

 coral, shell, or bone, which may be submitted to his inspec- 

 tion."* So also, the great cell doctrine which is now the 

 basis of animal physiology, had its origin in microscopical 

 investigations into the organization of plants. " Since it 

 ,has been ascertained that the animal tissues are in their 

 fundamental structure identical with the vegetable tissues, 

 we may expect that botanical investigations may throw as 

 much light upon the animal kingdom, as the study of ani- 

 mals may throw on the vegetable kingdom. Easy as it has 

 been to study the structure of vegetable tissues, so difficult 

 has it been to ascertain their functions, and the work of the 

 various organs in plants, that the most contradictory opi- 

 nions are entertained upon vegetable functions, upon the 

 circulation of their sap, upon their respiration, and the 

 action of respiration on their fluids. On the contrary, in 

 animal structures the functions are easily traced. The com- 

 bined action of the various functions upon each other can 

 be easily ascertained. It was the structure, the intimate 



* Lectures on the Comparative Anatomy and Physiology of the 

 Invertebrate Animals, delivered at the Eoyal College of Surgeons : hy 

 Richard Owen, F. R. S. 



