166 MINNESOTA BOTANICAL STUDIES. 



alcoholic solutions were used. Both staining the sections and 

 the material in toto were tried. In the latter method, if the ma- 

 terial was to be imbedded, it was first stained. If the stain is 

 sufficiently diluted, and the sections are allowed to stand in it 

 from ten minutes to half an hour, the results are quite as satis- 

 factory as staining in toto, for in the latter method often the stain 

 fails to penetrate the material completely. 



The stains employed were hasmatoxylin, anilin blue, methyl 

 blue, carmine, methyl violet, fuchsin and safranin. Hasma- 

 toxylin stains both cell wall and contents, but not clearly 

 enough ; it was found very unsatisfactory. Anilin blue and 

 carmine hardly affected the tissues. Methyl blue and safranin 

 proved good for the gelatinous sheath. Methyl violet and 

 fuchsin gave the most satisfactory results. They stain both 

 the cell walls and protoplasmic contents, but the latter more 

 deeply. These two stains, and especially fuchsin, were used 

 for all the work. 



The sections were at first taken from the knife and placed in 

 glycerine, transferring gradually from 20 per cent, to absolute, 

 but the glycerine was found to swell the cell walls to a consider- 

 able extent and was abandoned. 



The most satisfactory method and the one employed in all the 

 latter part of the work was as follows : The alcoholic material 

 was placed directly in the gum arabic solution on the freezing 

 chamber, transferred from the knife to the alcoholic solution of 

 the stain and mounted in it. When the staining was completed, 

 usually after a few moments, the sections were washed in alco- 

 hol. This was then evaporated and, without allowing the sec- 

 tions to become dry, glycerine jelly was added, making a per- 

 manent mount. 



BIBLIOGRAPHY. 



Jonsson, B. Beitrage zur Kenntniss des Dickenzuwachses der 

 Rhodophyceen. (Bot. Zeit. 50: 181. 1892.) (Bot. Jahresb. 19: 

 120 121. 1894.) Lunds Univers. Arskr. 27: 41. 2 pi. 189091. 



Wille, N. Beitrag zur Entwicklungsgeschichte der physiologischen 

 Gewebesysteme bei einigen Florideen. Nova Acta Acad. Leop.- 

 Carol. 52: 49-100. pi. 3-8. 1887. (Bot. Jahresb. 16: 754. 

 1891.) " 



Osterhout, W. J. V. A Simple Freezing Device. Bot. Gaz. 21 : 

 195-201. 1896. 



Schmitz, F. Die Gattung Actinococcus Kiitz. Flora. 77 : 367- 

 418. pi. 7. 1893. 



