Chapter XIV 



167 



The Vacuolar System 



longing to the tetragonal system; sometimes as crystal dust. The 

 crystals of calcium sulphate are also very frequently found (Clos- 

 terium, Spirogyra) . 



Fig. 112. — Lilium candidum. Lipide concre- 

 tions within the vacuoles. A, in epidermal cells 

 of the bulb; small granules (1) agglomerate into 

 mulberry-shaped masses (2), these, B. in older 

 scales become large bodies which are globular with 

 a denser center (4) or of radiating crystalline 

 structure (3). C, in drying outer scales, these 

 break up and myelin figures (5) appear which 

 finally, in dead cells, form masses of wound up 

 threads (6). 



Vacuolar pH and rH:- It is very difficult to obtain an exact idea 

 of the vacuolar pH. It has been seen indeed that the change of 

 color of the vital dyes has only a very questionable value. Then, 

 too, the indicators of pH do not penetrate into the vacuoles and are 

 besides very toxic. However, evaluations have been attempted by 

 Crozier, Haas and Irwin, who sought to extract the vacuolar sap 

 of certain algae, such as Valonia, in which the articulations are oc- 

 cupied by an enormous vacuole. These evaluations have shown 

 that the vacuolar ^^H in Valonia has an acid reaction (5.0-6.7). 

 Crozier, Haas and Schmidt have used an interesting method by 

 making the anthocyanin pigments serve as indicators. These pig- 

 ments can be extracted from the petals and in mixing them with 

 buffer solutions of known 2?H, all their different possible colors may 

 be obtained and consequently the coloring which the petals show 

 naturally may be related to a known pH. The results obtained by 

 this method inform us as to the vacuolar pH. It scales from 3.0-8.0. 



We have been able with Gautheret to find a way to evaluate 

 the vacuolar pH but only qualitatively. Clark and Perkins have 



