Chapter VIII 



77 



The Chondriome {cont'd) 



It is difficult to check these phenomena by observation of living 

 material. Roots in general do not lend themselves to this type of 

 investigation. On the other hand, in the course of our research, 

 we have found exceptionally favorable examples in which the entire 

 process of elaboration of starch can be followed with remarkable 

 accuracy in living cells. In a fragment of the epidermis of the 

 anther of a young flower of Iris germanica examined in Ringer's 

 solution, a chondriome is observed with great clearness, composed 

 of thin, elongated, and undulating chondrioconts which sometimes 

 branch, interspersed with granular mitochondria and short rods. In 

 some cells there is no elaboration of starch; in others there may 

 be seen several stages in the formation of small, compound, very 

 refractive starch grains on the long axis of the chondrioconts. 

 Similar phenomena may be observed in epidermal cells of the 

 leaves, of the bracts, and of all very young floral parts. At later 





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\ 



4i 



v7 * i f 



Fig. 40 (left). — Successive stages in the formation of leucoplasta in the 

 root of Phajtts grandif alius . Regaud's method. 



Fig. 41 (right). — Leucoplasta from the root of Phajus grandif alius showing 

 starch. 1, central cylinder; 2, cortical parenchyma. Regaud's method. 



stages of development it is seen that the starch grains are absorbed 

 within the chondrioconts which persist after the disappearance of 

 the starch (Fig. 44) . It can also be seen in these same cells that the 

 chondrioconts are, at certain stages, the seat of a production of 

 small osmium-reducing lipide globules, clearly visible on the long 

 axis of these elements because of their strongly refractive power. 

 These granules which often completely fill the chondriocont are very 

 frequent in the monocotyledons. They can not be considered as 

 formed of a-^ hexylene-aldehyde (Meyer), for they present char- 

 acteristics of lipides and not those of aldehydes. The fact that 

 they are stained by Dietrich's method suggests that they are ma(ae 

 up of phosphoaminolipides. These granules, very numerous in 

 the young stages of development of leaves, bracts and floral parts, 

 disappear from the plastids as soon as the starch grains and pig- 



