Guilliermond - Atkinson 



78 



Cytoplasm 



merits begin to form, except, however, in certain regions where they 

 persist during the entire hfe of the cells. Do they represent an 

 intermediate product from which starch and pigments are built 

 up, or do they result from a breaking down of the lipoprotein com- 

 plex which makes up the plastids (lipophanerosis) ? It is difficult 

 to say. In any case, these granules reappear in large numbers 

 in the plastids at the moment when the flower begins to form. 

 They are in this case products of disintegration of the plastids and 

 mark the beginning of plastidial degeneration. 



The epidermal cells of perianth parts of the tulip are also par- 

 ticularly favorable objects for observation of the living chondri- 

 ome and in them it is possible to follow the formation within the 

 chondrioconts of a yellow pigment, xanthophyll. In the white tulip, 

 for example, the chondriome can be observed very clearly in a frag- 





A 

 P 





oOOq 

 oqOO 



Fig. 42 (left) . — Epidermal cells of living young anther of Iris germanica, 

 showing refracting mitochondria, chondrioconts and strongly refracting lipide 

 granules. The two lower cells contain chondrioconts with small compound 

 starch grains (A) on their long axes. 



Fig. 43 (right). — Epidermal cells of leaves of Iris germanica. A comparison 

 of the chondriome in (6) a living cell with (a) one fixed by Regaud's method, 

 showing that the chondrioconts in (a) correspond to the plastids in (b) ; that 

 the rod-shaped and granular chondriosomes are similar in the two cells; that 

 the lipide granules appear only in (b) . c, d, e, similar portions of the cell 

 showing (c, e,) starch bearing plastids in living and fixed material (Regaud's 

 method) respectively: d, plastids not forming starch; /, g, successive stages in 

 the vesiculation of living plastids, C, chondriosomes; P, chondriocont, plastid; 

 Gl, lipide granules; A, starch. 



ment of the epidermis of the perianth. It is made up of a con- 

 siderable number of very elongated chondrioconts and granular 

 mitochondria. The bases of the perianth parts are almost always 

 yellow and, on examining the epidermis in this region, it is seen 

 that it is the chondrioconts which serve as substratum for the 

 xanthophyll pigment and consequently represent the chromoplasts. 

 The mitochondria, on the contrary, remain colorless. In yellow 

 flowers, however, the chondrioconts in all parts of the epidermis 

 appear yellow because of the xanthophyll. 



In living epidermal cells of the perianth and those of the exo- 

 carp of fruit of monocotyledons, the chondriosomes can be observed 

 with greatest ease and the formation of carotinoid pigments fol- 



