THE STRUCTURAL COMPONENTS OF PROTOPLASTS 



31) 



l)igmonts are mostly resjionsiljle for these colors in flowers and fruits. 

 Yellow flavone pigments rarelj^ arc evident in the sap of j^etals (e.g., 

 snapdragons), although they may be made to appear in some white flowers 

 upon hj'drolysis of the glucosides of which they are constituents. It is 

 rather the plastid pigments that give so many plants their yellow colors. 



Golgi Material. — The Golgi material, named after its discoverer, 

 appears in the cytoplasm of nearly all animal cells prepared with certain 

 special techniques designed to deposit silver or osmium 

 as a dark precipitate. Under such conditions the ma- 

 terial appears in the form of separate small bodies or as 

 a more or less continuous system of strands, these forms 

 being fairly constant in certain types of cell. Only 

 rarel}^ can it be distinguished from the c,ytoplasm in 

 living cells. Its composition is not well known, but 

 lipides are evidently present. Its tendency to show 

 blackened and nonblackened portions in silver-impreg- 

 nated material suggests the occurrence of two main con- 

 stituents which may not, however, have such an 

 arrangement in the' living cell. Its behavior in cen- 

 trifuged cells indicates its physical distinctness from 

 the chondriosomes and also that its viscosity in different 

 cells varies with respect to that of the cytoplasm. 

 At the time of cell division it is distributed passively 

 and more or less equally to the daughter cells (Fig. 28). 



The function of the Golgi material is most evident 

 in gland cells (Fig. 29). During secretory activity' in 

 these cells, it becomes more plentiful and droplets of 

 the secretion product make their appearance in contact 

 with it. The droplets accumulate near the surface of 

 the cell and are eventually excreted. It is not yet clear 

 whether this should be interpreted as a synthesis or a 

 condensation of the secretion globules by the Golgi 

 material, or w^hether the globules themselves, which 

 stain with neutral red, are active vacuoles in which the 

 secretion is produced from materials in the cytoplasm near l)y. On the 

 latter theory the Golgi networks seen in silver preparations are inter- 

 preted as an alteration of dense chondriosome-containing cytoplasm 

 between the vacuoles in this region of the cell. The rok^ of the Golgi 

 material in nonglandular cells is problematical, though secretory or other 

 elaborative activity on a smaller scale is suggested. 



Attempts to "homologize" the Golgi material with some constituent 

 of plant cells have not met with definite success. When meristematic 

 plant cells are treated with the special methods mentioned above, the 



Fig. 28.— Moi- 

 aphase of first divi- 

 sion in spermato- 

 cytes of a bug 

 (Euschistus) pre- 

 pared by dififerent 

 methods to show 

 filamentous chon- 

 driosomes (above) 

 and rounded Golgi 

 bodies (below) . 

 Chromosomes at 

 center. (After R. 

 H. Bowen.) 



