Chapter VIII 

 THE CHONDRIOME (Continued) 



The chondriome and its development in the phanerogams. 

 Relationships between chondriosomes and plastids. The facts :- 



The first investigations on this subject were those of Pensa 

 (1910). Applying the Golgi method to various tissues of phanero- 

 gams, i.e., impregnating sections of living phanerogam tissue 



'^i*vf?. 



Fig. 33. — Development of chloroplasts in a young leaf of 

 the plumule of barley. 1, chondriome in the basal meristem; 2, 

 cells beginning to differentiate with some elements of the chondri- 

 ome showing thickening, and 3-5 their transformation into 

 chloroplasts; 7, cells in older regions showing chloroplasts. c, 

 young chloroplasts; gc, mature chloroplast. Regaud's method. 



with silver nitrate followed by treatment with a reducing solution 

 of hydroquinone, he noticed that the chloroplast has the property 

 of reducing silver nitrate and appears strongly blackened by a 

 deposit of metallic silver on its substratum. Now, while studying 

 the chloroplasts in differentiating tissues, Pensa stated that these 

 elements appear first as very small bodies which present the form 

 characteristic of chondriosomes in animal cells. Yet this author 

 never reached the point of specifying the origin of these chon- 

 driosome-shaped elements. He did not find them in tissues lack- 

 ing in chlorophyll and stated that their property of reducing 

 silver nitrate is correlated with the presence of chlorophyll in 

 the substratum. Pensa, however, put forth the hypothesis that 

 the chloroplasts are derived from chondriosomes on which 

 chlorophyll accumulates, giving them the property of reducing 

 silver nitrate. 



