APPLICATION OF ABOVE DIRECTIONS IN CASE OF HYDROID 249 



tions stretch out flat, but do not melt the paraffin. Carefully 

 drain off excess water and set slides aside to dry. If the air 

 is dry, the slides should be ready for further treatment in 

 about twelve hours. The value of this method is that it gives 

 perfectly flat sections. At the end of this time the slides 

 may be placed in xylol to dissolve the paraffin. When the 

 paraffin is completely dissolved (this will take a few minutes) , 

 drain off the xylol, apply a drop of balsam, and cover as in 

 total mounts. The preparation is now ready for use, and is 

 permanent, but must be handled carefully while fresh. 



Application of Above Directions in the Case of a Hydroid : 

 Hot Bouin's picroformol, fifteen seconds. 

 Cold Bouin's picroformol, five to fifteen minutes. 

 Fifty per cent alcohol, four changes, three or four min- 

 utes each. 

 Seventy per cent alcohol, five minutes. 

 One half of your material may now be placed in borax car- 

 mine. Leave the material in this till objects have taken on 

 a good color. (Ask an instructor about this.) When suffi- 

 ciently stained, put into acidulated alcohol till the color as- 

 sumes a brilliant appearance, but do not allow it to fade too 

 far. Wash in 70 per cent and then run through 80 per cent 

 and 95 per cent alcohol, five minutes each, and mount directly 

 in euparal. 



If balsam is to be used, continue from the 95 per cent 

 alcohol to 100 per cent alcohol, five minutes, thence into 

 clove oil, or cedar oil, keeping all reagents carefully covered, 

 and leave till the object is thoroughly penetrated. This lat- 

 ter process may take five to ten minutes. 



If, on putting your objects into the clearing medium, the 

 latter exhibits a milky-white appearance, the material is not 

 sufficiently dehydrated, and must be returned to 100 per cent 

 alcohol. 



After clearing is completed, put the object on a clean 

 slide with a little balsam and cover. 



The material not treated with borax carmine may be run 



