showing mycelium, haustoria, and a spore-cluster; 3, a spore-cluster
seen from below; 4, a uredospore; 5, germinating uredospore; 6,
appressorial swellings at tips of germ-tubes; 7, infection through stoma
of leaf; 8, teleutospores; 9, teleutospore germinating with promycelium
and sporidia; 10, sporidia and their germination (2 after Zimmermann, 3
after Delacroix, 4-10 after Ward)]
Roasted date stones have been used as adulterants, and these can be
detected quite readily with the aid of the microscope, as they have a
very characteristic microscopic appearance. The epidermal cells are
almost oblong, while the parenchymatous cells are large, irregular and
contain large quantities of tannin.
Adulteration and adulterants are considered more fully in chapter XVII.
[Illustration: GREEN AND ROASTED COFFEE UNDER THE MICROSCOPE
Green bean, showing the size and form of the cells as well as the drops
of oil contained within their cavities. Drawn with the camera lucida,
and magnified 140 diameters.
A fragment of roasted coffee under the microscope. Drawn with the camera
lucida, and magnified 140 diameters.]
[Illustration: BOGOTA, GREEN
Longitudinal--Magnified 200 diameters]
[Illustration: BOGOTA, GREEN
Cross Section--Magnified 200 diameters]
[Illustration: BOGOTA, GREEN
Tangential--Magnified 200 diameters]
[Illustration: BOGOTA, ROASTED
Tangential--Magnified 200 diameters]
[Illustration: GREEN AND ROASTED BOGOTA COFFEE UNDER THE MICROSCOPE
These pictures serve to demonstrate that the coffee bean is made up of
minute cells that are not broken down to any extent by the roasting
process. Note that the oil globules are more prominent in the green than
in the roasted product]