Guilliermond - Atkinson 



— 168 



Cytoplasm 



shown that neutral red reduced in an alkaline medium (pB. 8.2 for 

 example) gives a leucoderivative which, by acidification of the 

 medium (pR 5.2 for example), is transformed into a second deriva- 

 tive, yellow in color and fluorescent, which is distinct from the 



Fig. 113. — Cells of stipe of 

 Laminaria flexicaulis. Bouquet 

 crystals formed by the pre- 

 cipitation of iodide by cresyl 

 blue in the vacuoles. P, 

 phaeoplast. lo, fat globule. 

 (After Mangenot). 



Fig. 114. — Epidermal cells of sepals. 

 Pigment in the vacuoles, partly in 

 solution, partly crystallized. 1-2 Del- 

 phinium. 1, D. Ajacis; pigment blue, 

 clusters of needle-shaped crystals. 2. 

 hort. var. with dark blue flowers; long, 

 entangled needle-shaped crystals. 3, 

 Verbena hybrid; large sphaerocrystals. 



Fig. 115. — Mycelium of Eremothecium 

 Ashbyii. a, vacuole with flavin in solution; 

 b, vacuole with flavin crystals; gl, lipide 

 granules. 



first. This latter is also obtained when neutral red is reduced in 

 an acid medium. Finally, although oxidation of the leucoderiva- 

 tive is rapid in contact with air, that of the fluorescent form is 

 very slow. Now, in treating wheat roots, or the epidermis of Iris 

 rich in phenolic compounds, with the leucoderivative of neutral 

 red, we have found that the vacuoles take a yellow coloration 

 which, in contact with the air, reddens only slowly. On the con- 

 trary, the cells of the bean root which are lacking in phenolic com- 



