442 MANIPULATION. 



seen in the interior of the kidney, as was first discovered by 

 Mr. Bowman, in the expanded extremity of a tubule 

 surrounding the plexus of blood-vessels forming the so-called 

 Malpighian body ; in order to exhibit the cUiary action, the 

 kidney is to have a few very thin slices cut from it, and these 

 are to be moistened with the serum of the blood of the same 

 animal, the vascular and secreting portions of the organ may 

 then be seen with a power of two hundred diameters, and also 

 the cilia in the expanded extremity of each tube, as it passes 

 over to surround the vessels; the epithelium of the tubes 

 themselves is of the spheroidal or glandular character. Since 

 Mr. Bowman's discovery, the phenomenon has been witnessed 

 in other animals in the same situation. 



The Basement Membrane, as before described, is structure- 

 less, and not suppUed in any way with vessels ; the best places 

 for viewing it are the tubes of the kidney and stomach, 

 and the villi of the small intestine ; in the skin and other 

 smooth surfaces, its presence cannot be so satisfactorily made 

 out. The examination of mucous surfaces and glands, 

 although conducted with great care by some of the earliest 

 microscopists, did not much advance the knowledge of their 

 minute structure, as the instruments employed for the purpose 

 were not suited for very accurate or minute investigation. 

 The principal point arrived at by them was the arrangement 

 of the capillaries, and as long ago as 1736 the art of injecting 

 the minute blood-vessels, which was discovered by De Grraaf, 

 in the year 1688, had been brought to such a high state of 

 perfection by Euysch and Lieberkuhn, that the fame of 

 their productions already extended throughout Europe : but 

 however much anatomists had made out by rough dissection 

 and maceration, it might be said with truth, that nothing 

 beyond the arrangement of the vessels was satisfactorily 

 known until the time of Boehm, Boyd, and Henle ; to the 

 latter distinguished anatomist we are chiefly indebted for our 

 knowledge of the structure known as epithehum. By new 

 modes of examination and dissection, as well as by submitting 

 very thin vertical and other sections to the high powers of the 

 achromatic compound microscope, has our present accurate 



