24 BOTANICAL MICROTECHNIQUE. 



at c, can easily be fitted laterally to any water-faucet. In 

 the zinc vessel the larger space d serves to hold the glass 

 drainers. If the water is to run rapidly from it, the pinch- 

 cock g is opened, so that the water runs out through the 

 tube f that communicates with the bottom of the vessel. 

 If the water is to run from it more slowly, the pinch-cock 

 g is closed, and the water can then escape only through the 

 tube e, whose mouth is 15 mm. above the bottom of the 

 vessel, so that the water stands 15 mm. deep on its bottom. 

 For the use of the space h, see 39. 



C. STAINING. 



36. If large objects have been fixed, it is usual, after 

 Avashing, to cut them into sections and to stain these. In 

 many cases, however, very good results are obtained by 

 staining the objects directly after washing and then pre- 

 paring sections from them. In case of this so-called stain- 

 ing in mass (" Stiickfarbung"), the slight permeability of the 

 cuticle must again be noted, and the penetration of the stain 

 must be aided by its entire removal or by slitting it. 



In many cases of mass staining it may be useful to obtain 

 on one and the same section all the different grades of stain- 

 ing side by side, the parts nearest to the surfaces being most 

 deeply stained, while the intensity of the stain gradually 

 decreases as the distance from the surface increases. 



If a large number of objects are to be stained at the same 

 time, one may conveniently use the glass drainer described 

 in 35. Especially with smaller parts 

 or sections of plants, one often finds 

 the glass vessel shown in Fig. n useful. 

 Its cover has a groove corresponding to 

 the edge of the dish.* 



If concentrated staining solutions are 

 used in this case, it is often difficult to 

 recognize the separate objects clearly. One may then find 



* [These so-called " Slender dishes," as well as the other items of glass- 

 ware described in these pages, may now be obtained of the leading American 

 dealers in microscopical supplies.] 



