

EPITHELIUM. 57 



feet, toey become flattened, dry, and horny ; in the interior of 

 the Cydy, on the other hand, where such conditions do not 

 exisf^they are succulent and pliable. 



Ordinary flattened or squamous epithelium. This is best 

 obtained by scraping the back of one' s tongue with a blunt 

 instrument. The scrapings should then be mounted in equal 

 parts of the common salt solution (i per cent.) and glycerine. 

 The epithelial bodies may in this way be readily studied. They 

 are separate or grouped together in collections of two or more. 

 In diameter they vary between -ffa-Q and -^ inch. The sur- 

 faces are all bevelled, and at the same time are uneven or 

 ridged ; consequently they overlap one another to a certain 

 degree, and the inequalities of one corpuscle fit into those of 

 another. The most superficial epithelium is the thinnest, and, 

 conversely, the deepest is apt to be the most nearly spheroidal. 



Intermixed in the mucus will be seen the so-called mucous 

 or salivary corpuscles. They are not very numerous, but are de- 

 tected by the "molecular" or Brownian movement of their in- 

 terior. In size they closely resemble the white corpuscles of the 

 blood, but, as a rule, exhibit no amoeboid motion ; the white glob- 

 ules, on the other hand, rarely have any Brownian movement. 



The surfaces of the epithelia are often so covered with bac- 

 teria that they are only recognized with some difficulty. These 

 little bodies are wonderfully uniform in size, and are disposed 

 in the most regular manner. .Looking straight down upon 

 them they appear to be minute spheres with a diameter aver- 

 aging between yyfonr and TT fonr inch - Closer inspection and 

 examination of the corpuscles at their free edges shows that 

 the bacteria are in reality rod-shaped, and that they adhere to 

 the corpuscles by their extremities, standing in such cases 

 vertical to the surface. A high power, such as the immersion 

 ^, develops this point quite clearly. 



Incidentally the mucin of the mucus may be seen to advan- 

 tage in the scrapings of the mouth or tongue. To a drop or two 

 add another drop of commercial alcohol and a drop of the or- 

 dinary hsematoxylin solution. The alcohol will coagulate the 

 mucin, which then takes the form of filaments and branching 

 networks ; the logwood will make them distinctly visible. 



Epithelium from the skin may be studied in one of two 

 methods. Take a fresh specimen from the palmar surface of 

 the hand or plantar of the foot, freeze it in a section cutter, 



