STARCH AND SUGAR: CHLOROPHYLL. 



69 



lower plants. This we have already seen in the case of 

 spirogyra, where the chlorophyll body is in the form of a very 

 irregular band, which courses around the inner side of the cell 

 wall in a spiral manner. In zygnema, which is related to 

 spirogyra, the chlorophyll bodies are star-shaped. In the 

 desniids the form varies greatly. In cedogonium, another of 

 the thread-like algre. illustrated in fig. 144, the chlorophyll bodies 



Fig 6911. 

 Section of ivy leaf, palisade cells above, loose parenchyma, with large intercellular spaces 

 in center. Epidermal cells on either edge, with no chlorophyll bodies. 



are more or less flattened oval disks. In vaucheria, too, a 

 branched thread-like alga shown in fig. 138, the chlorophyll 

 bodies are oval in outb'ne. These two plants, cedogonium and 

 vaucheria, should be examined here if possible, in order to be- 

 come familiar with their form, since they will be studied later 

 under morphology (see chapters on cedogonium and vaucheria, 

 for the occurrence and form of these plants). The tbrni of the 

 chlorophyll body found in cedogonium and \aucheria is that 

 which is common to many of the green algte, and also occurs in 

 the mosses, li\'erworts, ferns, and the higher plants. It is a 

 more or less rounded, oval, flattened body. 



145. Chlorophyll is a pigment which resides in the chloroplast. — That 



the chk)ro]-)]t}-ll is a culuriiig substance which resides in the chloroplastid, 

 and does not form the bod\* itself, am l:)e demonstrated b}' dissoUint,^ out the 

 chlot*oph)'ll when the fr.iniework of the chloroplastid is apparent. The 

 green parts of plants which have been placed for some time in alcohol lose 



