Guilliermond - Atkinson — 166 — 



Cytoplasm 



posed of thymonucleic acid, like those of animal cells, which ex- 

 plains why the Feulgen reaction is obtained just as well in plant, 

 as in animal, nuclei. In the Saprolegniaceae, finally, we have 

 found sphaerocrystals which appear to have some relation to the 

 phosphoaminolipides. 



The vacuoles contain, as well as the colloidal material just 

 discussed, numerous crystalloid substances. The most wide-spread 

 of these are organic acids, halogen salts, nitrates and phosphates, 

 sugars (saccharose, glucose, fructose, etc.), heterosides and pig- 

 ments. Among the halogen salts we must mention the presence of 



iodide in a dissolved state in the vacuo- 

 lar sap of numerous marine algae (Rho- 

 dophyceae and Phaeophyceae) . Its local- 

 ization in the vacuole may be demon- 

 strated in vivo by cresyl blue. This pig- 

 ment in the presence of iodized solu- 

 tions forms red crystals (Fig. 113) ar- 

 ranged in the shape of a bouquet (Sau- 

 VAGEAU and Mangenot). Among the 

 pigments may be mentioned the oxy- 

 flavanol pigments which are very pale 

 yellow in color and the anthocyanin pig- 

 ments which are red, violet, or blue. 

 Both types are extremely widespread 

 in green plants. Anthocyanin pigments, 

 when found in high concentration in 

 the vacuole, may crystallize there in 

 the form of needle-shaped crystals or 

 sphaerocrystals (Fig. 114). These two 

 types of pigment show histochemical 

 characteristics closely allied to tannins 

 (darkening with ferric salts, blackening 

 with osmic acid). The flavins may also 

 be cited. These are yellow pigments 

 playing at the same time the role of 

 hydrogen carriers and the role of Vitamin Ba. We have recently 

 found them in great abundance in the vacuoles of a fungus Eremo- 

 thecium Ashbyii where they crystallize in the form of needles or 

 sphaerocrystals. The alkaloids are very wide-spread in the vacuoles 

 of the phanerogams and may be recognized by testing with iodine- 

 potassium iodide (Bouchardat's reaction), which precipitates the 

 alkaloids in the vacuoles as brown granules. 



In bringing this inventory to a close, there must be mentioned 

 asparagine crystals and leucine crystals (lozenge-shaped or sphae- 

 rocrystals) and especially calcium oxalate crystals. These latter 

 are found in the vacuoles of a great number of phanerogams, some- 

 times as long needles (calcium oxalate monohydrate or acid cal- 

 cium oxalate) belonging to the monoclinic series; sometimes in the 

 state of octahedral crystals, isolated or twinned — quadratoctahedra, 

 in the nature of crossed twins (calcium oxalate trihydrate) — be- 



FiG. 111. — Diagrams of barley 

 root vitally stained with neutral 

 red and centrifuged. The chondrio- 

 some-shaped vacuoles of the meri- 

 stem, heavier than cytoplasm, are 

 displaced centrifugally; those tak- 

 ing in water in the region of 

 differentiation are not affected: 

 those still higher in the root, lighter 

 than cytoplasm, are displaced cen- 

 tripetally. (After Milovidov) . 



