Freeman: observatioxs on constantinea. 181 



A number of staining fluids were used, section staining, 

 either on or off the slide proving more satisfactory than stain- 

 ing in toto. Aniline stains were used almost exclusively. The 

 following were employed with at least some degree of success : 



Aniline blue : Stains the gelatinous wall of the cells pale 

 blue, the chromatophores of the cortical cells deep blue and the 

 contents of the tetraspores and of the paraphyses light blue. 

 The central part of the pyrenoids of the endophytic alga which 

 is usually present in these collections takes on a light blue. The 

 best results were obtained with a 40 or 60 per cent, alcoholic 

 solution, acting from 24 to 36 hours. For sections on the slide 

 5 to 10 minutes in a strong 60 per cent, alcoholic solution was 

 usually sufficient. INI}' best staining results were obtained from 

 aniline blue. 



Methylen blue : Stains the cell walls, especially the outer 

 portions, which become quite clearly defined. Sections were 

 stained in a strong 95 per cent, alcoholic solution from 5 to 10 

 minutes. 



Fuchsin : Best results were obtained from sections left in a 

 10 per cent, alcoholic solution 36 hours. The gelatinous walls 

 were stained light red while the protoplasm of the paraphyses 

 and chromatophores of the cortical cells took up a deep carmine 

 red. 



Delafield's hgematoxylin : Same strength and time as fuchsin. 

 The granular contents of the cells are stained a reddish purple. 



Several other stains were used, but without success. In a 

 weak solution of iodine in potassium iodide the granules of the 

 cells of the middle and intermediate layers assume at first a yel- 

 lowish-brown tinge which finally deepens to an amethj'st purple. 

 Stained in a strong solution for a few moments these areas take 

 on a dense violet color. 



Gross Anatomy. — In generalform Constantinea presents sev- 

 eral interesting peculiarities. (Figs. 1-6.) The plant is differen- 

 tiated into a cylindrical stipe and peltate frond at its summit. It 

 is of a purple-reddish color, stands upright in the water below 

 lowest low tide mark, and the texture is quite firm and brittle. 

 It is somewhat gregarious in habit. The stipe is " terete, 

 branched, ringed and the apex of each branch expanded into an 

 orbicular peltate lamina; stipe 1-4 mm. in diameter, 2-8 cm. 

 in length ; lamina 2 cm. -3 dcm. in diameter." (Tilden, Am. 

 Alg. no. 203. 1897-) The laminae have numerous minute 



