GENERAL REMARKS ON STAINING 79 



then try the phloxine and aniUne-blue combination. Do not pass judg- 

 ment against a standard method or even a new method just because 

 you fail to get results at the first trial. After you have become pro- 

 ficient with the iron-alum haematoxylin for mitotic figures in higher 

 plants, you are sure to fail if you try the same procedure with Rhizo- 

 pus; but, nevertheless, the stain is just as good for Rhizopus as for 

 figures in pollen mother-cells or root-tips. 



Permanent preparations are such a necessary part of most advanced 

 work that one is in danger of delaying the critical observation until he 

 has made a permanent mount. It cannot be repeated too often that 

 one should develop also the technique of studying the living structures. 

 It is impossible to make a permanent mount of the rotation of proto- 

 plasm. Study motile spores while they are moving before you make 

 permanent preparations. The difficult and complicated histological 

 technique loses much of its value unless it is accompanied by a thor- 

 ough study of living material. 



