All about coffee by William H. Ukers

has since been found in nearly all coffee-producing countries, it has become a nightmare in the dreams of all coffee planters. The microscope shows how the spores of this dreaded fungus, carried by the winds upon a leaf of the coffee tree, proceed to germinate at the expense of the leaf; robbing it of its nourishment, and causing it to droop and to die. A mixture of powdered lime and sulphur has been found to be an effective germicide, if used in time and diligently applied. [Illustration: Fig. 337. Coffee. Spermoderm in surface view. _st._ sclerenchyma; _p_, compressed parenchyma. x160. (Moeller)] [Illustration: Fig. 338. Coffee. Cross-section of outer layers of endosperm, showing knotty thickenings of cell walls. x160. (Moeller)] [Illustration: Fig. 339. Coffee. Tissues of embryo in section. x160. (Moeller)] _Value of Microscopic Analysis_ The value of the microscopic analysis of coffee may not be apparent at first sight; but when one realizes that in many cases the microscopic examination is the only way to detect adulteration in coffee, its importance at once becomes apparent. In many instances the chemical analysis fails to get at the root of the trouble, and then the only method to which the tester has recourse is the examination of the suspected material under the scope. The mixing of chicory with coffee has in the past been one of the commonest forms of adulteration. The microscopic examination in this connection is the most reliable. The coffee grain will have the appearance already described. Microscopically, chicory shows numerous thin-walled parenchymatous cells, lactiferous vessels, and sieve tubes with transverse plates. There are also present large vessels with huge, well-defined pits. [Illustration: COFFEE LEAF DISEASE (HEMILEIA VASTATRIX)