X 
Journal of Agricultural Research 
Vol. VII 
Grain of the Tobacco Leaf 
Page 
Plate 15. A, B.—Well-cased tobacco leaves stretched over the closed end of 
a test tube; showing very pronounced grain development. C.—A portion 
of a cigar wrapped with a leaf containing very coarse grain. D.—The 
same as figure C, but after a portion of the cigar had been smoked, showing 
the white pimples in the ash produced by the burning and swelling of the 
grain bodies. % .. 288 
Plate 16. A.—Grain bodies of Connecticut Broadleaf tobacco as seen in ordi¬ 
nary transmitted light, a, Idioblasts containing sand crystals of calcium 
oxalate. B.—Representative grain bodies of class 1. C.—Representa¬ 
tive grain bodies of class 2. D.—Representative grain bodies of class 3. 
E.—Representative grain bodies of class 4. F.—Grain substance in the 
form of minute spherites. 2 88 
Plate 17. A.—Green tobacco leaf killed in absolute alcohol and showing idio¬ 
blasts of calcium oxalate and minute, scattered, single crystals of an unde¬ 
termined substance, but no grain. B.—Representative sample of the 
poor burning 1909 Pennsylvania tobacco. C.—Flue-cured tobacco. Poor 
burning. D.—Connecticut Broadleaf tobacco. Good burning. E.— 
Fermented tobacco. Poor burning. F.—Fermented tobacco. Good 
burning. G.—Tobacco. Cured only. 288 
Host Plants of Thielavia basicola 
Plate 18. Fairly typical diseased spots and lesions caused by Thielavia basicola 
on various host plants. A.— Citrullus vulgaris . B.— Onobrychis viciae- 
folia . C.— Lupinus luteus. D.— Arachis hypogaea . E*— Robinia pseudo¬ 
acacia. F.— Sclotis chinensis . 300 
Plate 19. A.—Part of a field infected with Thielavia basicola in foreground, 
with newer soil planted to tobacco in the background, illustrating the 
marked pathogenic powers of this organism. B,—A tobacco plant showing 
diseased roots from infected soil. C.—Healthy roots from uninfected soil 
of a semiresistant type of tobacco. Figures B and C show the relative 
growth of plants and amount of root system after equal care in removing 
roots from the soil. 300 
Rosy Apple Aphis 
Plate 20. A. — Aphis sorbi: Spring migrant. B.— Aphis kochii: Spring mi¬ 
grant. C.— Aphis malifoliae: Spring migrant. 344 
Plate 21. Aphis t malifoliae: A.—Fall migrant. B.—Male. C.—Spring wing¬ 
less female. D.—Intermediate form... 344 
Plate 22. A.— Aphis malifoliae: Summer wingless form, A.— Aphis malifoliae: 
Oviparous female. C.—Structural details of Aphis malifoliae , A. sorbi , 
and A. kochii. a, A. sorbi: Segment VI of antenna of winged form, b, A. 
malifoliae: Cornicle of spring wingless form, c, A. malifoliae: Cornicle of 
summer wingless form. d t A. malifoliae: Cauda of summer wingless form. 
e, A. malifoliae: Cauda of spring wingless form. /, A. malifoliae: Segment 
VI of antenna of winged form, g, A. malifoliae: Segment VI of antenna of 
stem mother. h f A. kochii: Segment VI of antenna of winged form, i, A. 
sorbi: Cauda of winged form, j, A. kochii: Cornicle of spring migrant. 
k, A. sorbi: Cornicle of spring migrant. l f A. malifoliae: Cornicle of spring 
migrant, m , A. sorbi: Segment III of antenna of spring migrant, n, A. 
malifoliae: Segment III of antenna of spring migrant. 344 
Plate 23. Aphis malifoliae on its alternate host, Plantago lanceolata . 344 
