124 MANUAL OF HISTOLOGY. 



hud failed to see, were investigated a few years ago by Long- 

 worth, of Cincinnati, and their existence established as a matter 

 of no doubt. He took the human eye, freshly removed with 

 the conjunctiva, and made the examination immediately. At- 

 taching the conjunctiva with threads, so that it preserved its 

 natural tension, he immersed it in a per cent, solution of os- 

 mic acid, or exposed it to the vapor of the same solution. 

 After twelve to twenty-four hours the membrane was deeply 

 stained, and the epithelium could usually be removed with 

 a brush or the finger-nail. Next, a thin piece of cornea was 

 removed and examined in water, or in 1 to 2 per cent, acetic- 

 acid solution. It was then mounted in glycerine. This method 

 was preferred to the gold chloride. In some conjunctive they 

 were found almost entirely absent ; in others, or in certain por- 

 tions, quite numerous. The entire interior was seen to be filled 

 with nucleated corpuscles. Waldeyer, in commenting on the 

 work of Dr. Longworth, agreed to it fully, and retracted his 

 former opinions. He places these bodies intermediate between 

 the tactile and Pacinian bodies. 



The tactile corpuscles of the skin (called also Meissner's 

 or Wagner's corpuscles) are to be seen in the papillae, and 

 especially well in the tips of the fingers, and in the internal 

 genitals. They have a length of about -^ millimetre. Speci- 

 mens hardened and preserved in the ordinary way show them 

 well. They are oblong, rounded, and marke4 by transverse 

 wavy lines. A nerve-fibre may be seen running into their 

 centre. 



The Pacinian bodies, discovered by Vater, in 1741, but first 

 carefully described by Pacini, of Pisa, are oval or pear-shaped 

 bodies, attached to the nerves like berries to a stem. They are 

 found in the subcutaneous tissues of the finger (Kolliker), in 

 the labia majora, prostate, corpora cavernosa, and in many 

 other places. They are seen to the best advantage, however, 

 in the mesentery of the cat, where they are so large as to be 

 easily visible to the naked eye. 



Cut out a small piece of the mesentery, place it in a weak 

 solution of osmic acid (1100), and after a few minutes, when 

 it has become brown, detach the capsule carefully with needles. 

 Mounting at once in glycerine, the whole interior of the Paci- 

 nian will be superbty shown, constituting one of the most beau- 

 tiful specimens in histology. The medullated nerve may be 



