208 MINNESOTA BOTANICAL STUDIES. 



solution, thence, after washing, back to the gh^cerine solution. 

 The glycerine solution was allowed to concentrate by evapora- 

 tion, and the sections were thence mounted into glycerine jelly. 

 Portions of the frond were also embedded in pith and cut free- 

 hand with the razor. 



Some of the material was embedded in paraffine, according 

 to the usual methods and cut on the microtome. The sections 

 thus obtained proved, in some instances, very successful, espe- 

 cially in the case of such firm tissues as the stipe and the vege- 

 tative portions of the lamina. 



Several staining fluids were used. Both section-staining and 

 staining in toto were employed. The former method proved 

 most successful. The following stains were found useful. 



Aniline blue : Sections were placed for 5-10 minutes in a 

 saturated solution of aniline blue (spiritlos) in 50 per cent, alco- 

 hol. The walls were stained a deep blue, gelatinous structures 

 and cell contents a light blue. This proved the most useful 

 stain for clearly defining anatomical details. 



Hoffman's violet : Sections were stained with a saturated so- 

 lution of Hoffman's violet in concentrated sulphuric acid. As 

 soon as the section had taken a brown stain they were placed 

 in water and the acid washed out. The protoplasm took a blue 

 stain, the walls were unstained. This method proved useful 

 in staining the protoplasmic connections between the cells. 



Fuchsin : Dilute alcoholic solution of fuchsin stained the 

 walls light red, the protoplasmic contents a deeper red. 



Iodine in potassium iodide : This stained the floridian starch 

 a dark yellow-brown, the other cell contents a light yellow- 

 brown. It proved very useful in staining the protoplasmic con- 

 nections between the cells, especially in the gonimoblast fila- 

 ments. 



Gross anatomy (Fig. i). — The plant consists of a broad, flat, 

 membranaceous, more or less subdivided, blood-red lamina borne 

 upon a short stipe which is sensibly continuous with the lamina. 

 The stipe is expanded below into a small holdfast. The lamina 

 is sometimes nearly entire in outline, ovate, or broadly lanceo- 

 late, sometimes very deeply lobed, or divided almost to the base 

 into 2—4 lobes which may be widely divergent. The lamina is 

 17-40 cm. long and S-17 cm. wide. The two faces of the 

 frond are in all respects similar. The lamina is perforated by 

 numerous holes ranging from .5 inm. to 10 cm. in length and 



