130 THE MICROSCOPIST. 



of organized bodies are identical with the elements of other 

 bodies ; and the microscope detects the earliest forms produced 

 by the vital process, and the part sustained by them in the 

 development of each species. 



Chemical analysis shows, that what are termed simple ele- 

 ments, as oxygen, hydrogen, carbon, nitrogen, sulphur, &c., are 

 peculiarly arranged in all organized bodies; having special 

 affinities which they do not possess in unorganized substances, 

 or bodies destitute of life. These peculiar affinities form a class 

 of compound substances called proximate principles, or organic 

 compounds, or organizable substances. They are obtained by 

 the analysis of organized textures : such are albumen, fibrin, 

 starch, gluten, &c. 



Owing to the feeble affinity of the simple elements in the 

 organic compounds, there is a great tendency in them to enter 

 into new combinations, forming what are called secondary 

 organic compounds. Such are urea, uric acid, pepsine, sugar 

 of milk, &c. 



Hitherto, no one has succeeded in producing the true proxi- 

 mate principles by chemical synthesis, and it is doubtful if they 

 will ever be produced elsewhere than in the living organism. 

 Some of the secondary organic compounds have, however, been 

 formed in the laboratory of the chemist ; as the production of 

 urea from cyanate of ammonia through the action of heat, which 

 has been effected by Wbhler. 



" The simplest and most elementary organic form with which 

 we are acquainted, is that of a cell, containing another within 

 it (nucleus), which again contains a granular body (nudeolus)" 

 See Fig. 39. 



" This appears, from the interesting researches of Schleiden 

 and Schwann, to be the primary form which organic matter 

 takes when it passes from the condition of a proximate 



