184 



L. HILLIS-COLINVAUX 



Fig. 55. H. monile. Filament from a matm-e segment but one which is less than 48 hours 

 old. There appears to be much cytoplasmic activity in material of this age. Mature 

 chloroplasts (c) are present as well as iinmature ones, although the latter are not 

 present in the photomicrograph. Calcification has begun, but the crystals (cr) were 

 lost in sectioning, a = Amyloplast, e = electron-dense body, m = mitochondrion. 

 Stained with lead tartrate. Scale bar is 1 [xm. 



Although the full range of organelles may occur (Fig. 55), there is 

 also a gradient in the kinds of organelles predominating from periphery 

 to centre of the mature segment, the chloroplasts being commonest 

 towards the periphery and amyloplasts commoner in inner regions, but 

 since the chloroplasts migrate inward at night (Stark et al., 1969) and 

 amyloplasts presumably migrate too, the picture is not so simple. 



