658 THE MICROSCOPE. 



ultimate element of every gland is a simple sacculated 

 membrane, to which, the blood-vessels have access ; and 

 that all glands are formed from a greater or less number, 

 or different arrangement only of the primary structure. 



Our notions respecting the skin were vague until the 

 microscope discovered its real anatomy, and showed us 

 the existence and relations of the papillae, of the sudorific 

 organs and their ducts, the inhalent muscular apparatus, 

 and so on. All our knowledge of epidermic structures, 

 such as hair, horn, feather, &c, the real structure of 

 cartilage, bone, tooth, tendon, cellular tissue, and, in a 

 word, of all the solid textures, has been revealed to us by 

 the same agency ; so that it may be truly said, that all our 

 real knowledge of structural anatomy, and all our acquaint- 

 ance with the true composition of every organ in the body, 

 have been arrived at by means of the microscope, and 

 could never have been known without it. 



In addition to this, and what is of greater importance, 

 after having studied the healthy structure of the body, 

 most beneficial aid is afforded in the investigation of 

 changes produced by disease. We may cite one notable 

 example. Dr. Andrew Clarke, after having carefully 

 studied the appearances of sputa from patients under his 

 care, says, " that the microscopical inspection of expecto- 

 ration affords, at a very early period of consumption, defi- 

 nite information, not otherwise attainable, regarding the 

 nature of the malady ; and at all times must furnish 

 valuable aid in forming a prognosis regarding the cause of 

 the complaint." The expectoration generally shows pus, 

 cells, lung tissue, blood corpuscles, and granular material, 

 mixed with, at times, a small amount of fat corpuscles. 



The space allotted to this division of our subject enables 

 us to give only a short and imperfect sketch of a few of 

 the fundamental tissues of the animal body. First, enu- 

 merating merely the elementary substances recognised by 

 chemistry as entering into the formative processes, we shall 

 proceed to inquire into that most interesting and wonderful 

 starting-point of life, the cell ; admitted to be, and indeed 

 demonstrable as, the common centre alike of animal and 

 vegetable organisms. 



