42 MINNESOTA BOTANICAL. STUDIES. 



inner cells of the conceptacle, the paraphyses, oogonia and 

 antheridial hairs stain light red, the deeper cells of the con- 

 ceptacle purplish, the pith cell walls dark red, while the color 

 is all washed out of the matrix. Differentiation is also pro- 

 duced between different cortical layers, epidermis and cuticle 

 and pith. 



Methyl blue alone is a fairly good wall stain, but must be 

 washed with care or it will all wash out. It also stains the 

 chromatophores deeply. In this way the nuclei in the not too 

 opaque oogonia may be located, they shining through as lighter 

 areas in the dark mass of the oogone. Methyl violet is a 

 quick stain. Over-stain and wash out as desired. 



Bismarck brown was a very satisfactory stain for mapping out 

 cell structure distinctly. It stains the inner wall of the cells 

 (dark) brown, and the pith yellow. It is also useful in studying 

 the structure of the conceptacle, the gelatinous sheath around 

 the oogone being nicely brought out. It is a quick stain. 



It may either be used dilute and allowed to stain longer, or 

 more concentrated and then washed out till desired effect is ob- 

 tained. Either way is good. 



Hematoxylin dyes are better than carmine for nuclei. The 

 most satisfactory results were obtained by bleaching the sections 

 in chlorine gas for ten to fifteen minutes, then staining from one 

 to two days in hematoxylin, then washing out till the walls and 

 matrix were nearly clear, while the nuclei retained the stain 

 longer. The chromatophores stain in hematoxylin and thorough 

 washing is necessary to make the nuclei appear. Delafield's 

 hsematoxylin was found a good kind. The best effect was 

 obtained by using a hematoxylin (brand unknown) that had 

 been kept in solution at least ten years. 



Iodine is very satisfactory for staining the protoplasm, and is 

 very helpful in studying the pits between the cells, and in 

 studying the contents of the conceptacular organs. 



The staining was done on the slide. Rather concentrated 

 dyes were employed. For alcoholic solutions of dyes 70 per 

 cent, alcohol was used. 



