96 



PRACTICAL HISTOLOGY. 



keep the beaker of acidulated water in which the tissue 

 is placed warm, as this materially facilitates the reduc- 

 tion of the gold. For this purpose it is well to have some 

 arrangement by which the beaker, or several of them, if 

 there be much of the same sort of work going on, can be 

 kept at a temperature of about 30 or 40 Centigrade, 

 and at the same time freely exposed to the light. Fig. 

 19 represents a convenient apparatus for this purpose. 

 It is made of zinc or tinned iron with loose glass sides 

 and top, and may be fitted with a gas regulator (Fig. 20) 

 to prevent the temperature from rising too high. When 

 used for the present purpose the apparatus should of 

 course stand in a good light in the window if possible. 



n, a, small iuuer tube, capable of being slipped up 

 or down withia c, the upper part of the bulbed 

 tube containing mercury, d, small aperture to 

 allow of the constant passage of a small amount of 

 gas, so that the flame is not entirely extinguished 

 if the mercury should rise sufficiently high to 

 entirely exclude the lower end of the tube a. 

 The tube b, with the corks d nod e, form a simple 

 and easily constructed arrangement (suggested by 

 Mr. F. J. M Page) which serves as a gas-tight 

 telescopic joiat, and enables the tube a to be 

 raised or lowered according as the temperature of 

 the chamber is desired to be higher or lower. In 

 all other respects the working of the regulator is 

 similar to that belonging to the apparatus shown 

 in Fig. 9. 



The upper part of the raercural gas-regulator of the apparatus shown in 

 Fig. 19. Natural size. 



Preparations 6 and 7. Costal Cartilage. The 



cartilages of the ribs and those of the trachea and 

 larynx may be prepared and examined in a manner 

 similar to that recommended for the study of articu- 

 lar cartilage. Sections, both parallel and vertical 

 to the surface, should be made from the fresh tissue 

 and from pieces which have been a longer or shorter 



