l62 



COLLODION SECTIONIXG. 



[_CH. VII. 



of water. They may then be counterstained for half a minute with 

 some general dye, like eosin or picric acid, or mounted with but the one 

 stain.* 



Fig 134. Waste Bowl ivith rack for supporting slides and a small funnel in 

 which the slides stand while draining. This outfit is easily made by any tin smith. 

 The rack is composed of two brass rods about 3 mm. in diameter. The bent end 

 pieces are sheet brass. The futinel is made of tin, copper or brass. Either copper 

 or brass is preferable to tin. A glass dish like that shown in Fig. 135 is better than 

 a bowl, as it can be more readily and thoroughly cleaned. {Cut loaned by Win. 

 Wood & Co.). 



Fig. 135. Round glass aquarium. This glass vessel is better than the bowl for 

 all the uses described for the bo7vl. ( Whitall, Tatum & Co. ) 



Fig. 136. Glass box with cover. These boxes may be had of various sizes and 

 can be used advantageously for water, and for cleaning mixture for slides and 

 cover-glasses (\ 227). ( Whitall, Tatum <Sf Co.) 



* In the past the plan for changing sections from 95% alcohol to water, for ex- 

 ample, has been to run them down gradually, using 75, 50 and 35% alcohol suc- 

 cessively. Each percentage may vary, but the principle of a gradual passing from 

 strong alcohol to water was advocated. On the other hand, I have found that the 

 safest method is to plunge the slide directly into water from the 95% alcohol. The 

 diffusion currents are almost or quite avoided in this way. There is no time for 

 the alcohol and water to mix, the alcohol is washed away almost instantly by the 

 flood of water. So in dehydrating after the use of watery stains, the slide is 

 plunged quickly into ajar of 95% alcohol. The diffusion currents are avoided in 

 the same way, for the water is removed b) r the flood of alcohol. This plan has 

 been submitted to the severe test of laboratory work, and has proved itself perfectly 

 satisfactory. 



