Guilliermond - Atkinson 



80 — 



Cytoplasm 



starch grains. Then, when the starch is absorbed, the chondrio- 

 cont thickens at the same time that large vesicles appear along the 

 element. These may disjoin by a rupture of the more slender por- 

 tions of the chondriocont which connects them, so that vesicular 

 chromoplasts are formed with tails of varying lengths. In other 

 cases the pigment begins to appear in chondrioconts which increase 

 their dimensions proportionally as the pigment develops, until 

 they have been transformed into large chromoplasts of the same 

 form and dimensions as chloroplasts. 



Fig. 46 (left). — Transformation of chondrioconts into chromoplasts in living epidermal 

 cells. 1, formation of starch in very young petals; 2, starch being absorbed and replaced by 

 small granules and needle-shaped carotinoid pigment in older petals; 4, the same in an open 

 but young flower; 5, chromoplasts in an older flower. 1, 2, Clivia nobilis. 4, 5, C. cyrtanthi- 

 flora. 



Fig. 47 (right). — Development of chromoplasts in living cells of the fruit of Asparagus 

 officinalis. 1, chondrioconts forming starch; 2, starch being absorbed; 3, carotin granules 

 forming on the borders of vesiculate swelling in the plastids; 4, fragmentation of chondrioconts 

 to form round vesiculate plastids containing carotin granules which tend to fuse; 5, chromo- 

 plasts and chondriosomes in a cell of the pericarp of a nearly ripe fruit. 



Xanthophyll always seems to be diffuse in the substratum of 

 the plastid or else in the state of indistinct granules. Its iso- 

 mer, rhodoxanthin, on the contrary, appears as isolated, clearly 

 distinguishable granules. This is true of carotin and lycopin 

 if they are not in crystalline form. When crystalline, the crystals 

 give widely-differing shapes to the chromoplasts. These facts show 

 that whenever the chromoplasts do not arise by metamorphosis of 

 the chloroplasts as in the parenchymatous tissue, studied especially 

 by ScHiMPER, Meyer, and Courchet, they arise from chondrio- 

 conts which have first elaborated starch. 



