Guillierrnond - Atkinson 



164 



Cytoplasm 



are often associated or combined with tannins and perhaps with 

 mucilages. Lloyd and various other authors have shown that 

 tannin is often combined with mucilages in the state of a com- 

 plex, and it is thought that the vacuoles containing raphides en- 

 close mucilages. Furthermore, recent work has shown that in 

 certain cells the vacuoles contain a colloidal solution of phytosterol 

 or of phosphoaminolipides. These substances may become par- 

 tially solid in the epidermal cells of the Liliaceae (Fig. 112) . These 

 cells ordinarily contain a large inclusion, formed of a complex of 

 phytosterol and of phosphoaminolipides, which Mirande described 

 for the first time under the name of sterinoplast. This, he considered 



Fig, 109. — Rose. Cells from a tooth of a leaflet under the 

 ultramicroscope, showing faintly luminous contours of the vacu- 

 oles (V) and of the nuclei (N) . 1, tip of tooth. 2-4, 

 differentiated cells. 



to be a cytoplasmic inclusion, a sort of plastid, elaborating phy- 

 tosterol. The work of Miraton and of Emberger has demon- 

 strated that the sterinoplasts are not simple vacuolar concretions. 

 The recent work of Reilhes has established the fact that the vacu- 

 olar sap of these cells contains a solution of phosphoaminolipides 

 and of phytosterol which, in mature cells, becomes partially solidi- 

 fied in the vacuoles in the form of large bodies composed of a phos- 

 phoaminolipide-phytosterol complex. Inclusions, apparently of the 

 same nature, have been cited in the vacuoles by other authors : in 

 the epidermis of Iris, especially, in which they absorb anthocyanin, 

 when the vacuoles contain the pigment, and have been described 

 under the misnomer of cyanoplasts (Politis). Similar inclusions 

 have also been described in the epidermis of the flowers of Del- 

 phinium cultorum (SCHARINGER). We have shown as well that 

 in the cells of the root cap of barley and of wheat, there are 

 phosphoaminolipide solidifications and, by cultivating barley roots 

 in media very rich in sugar, Gautheret succeeded in making a great 

 number of lipide concretions appear in the vacuoles of most of the 

 cells. The vacuoles of Monotropa according to Weber contain large 



