VEGETABLE CYTOLOGY 
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Oleoresins are mixtures of oil and resin. Examples: Terebin- 
thina, Terebinthina Canadensis. 
Gum resins are natural compounds of resin, gum and oil. Ex- 
amples: Asafoetida, Myrrha, Cambogia. 
Balsams are mixtures of resins with cinnamic or benzoic acid or 
both and generally a volatile oil. Examples: Balsamum Tolu- 
tanum, Styrax, Balsamum Peruvianum. 
If sections of a resin containing plant part are placed in a saturated 
aqueous solution of copper acetate for a week or two and mounted 
in dilute glycerin, the resin will be stained an emerald green. 
21. Pigments. — These are substances which give color to various 
plant parts in which they are found. They occur either in special 
protoplasmic structures as chloroplasts, chromoplasts or chroma- 
tophores or, dissolved in the cell sap. Of the pigments named the 
following will be considered: Chlorophyll, Xanthophyll, Chromo- 
phyll, Etiolin, Anthocyanin, Phycocyanin, Phycophaein and Phy- 
coerythrin. 
Chlorophyll is the yellowish-green pigment found in the chloro- 
plastids or chromatophores of leaves or other green parts of plants. 
Its composition is not definitely known although it yields products 
similar to the haemoglobin of the blood when decomposed. Iron 
is known to be essential to its formation. If an equal portion of 
xylene be added to a fresh alcoholic solution of chlorophyll and the 
mixture shaken, The chlorophyll in solution will break up into a 
yellowish and greenish portion. The greenish portion dissolves in 
the xylene which rises forming the upper stratum while the yellowish 
portion dissolves in the alcohol forming the lower stratum. To this 
isolated greenish portion of chlorophyll has been given the name of 
“chlorophyllin” while the yellowish portion has been designated 
“xanthophyll.” 
Chlorophyllin when examined spectroscopically produces absorp- 
tion bands in the red, orange, yellow and green of the spectrum, the 
broadest and most distinct band being in the red. 
Chromophyll also called “ xanthophyll ” and “carotin” is the yel- 
low or orange pigment found in chromoplastids. By some the 
term carotin is limited to the orange pigment found in the carrot. 
Sulphuric acid forms a blue color with chromophyll. 
