XVI 
Fig. 
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33. 
w 
34, 
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LIST OF ILLUSTRATIONS 
Peg or rake steam sterilizer used by some growers at 
TNoledo,: Ohio) a2 225 22233252 ee ee ees 
Peg steam sterilizer in operation at Toledo, Ohio__----- 
Apparatus for formalin sterilization. (W. T—Water 
Tank. F. T.—Formalin Tank. G—Waterglass gauge 
to show quantity of formalin. A.—Air cock. V— 
Valve. F.—Funnel. E—-Air pipe to maintain same 
pressure in both tanks. D.—Drain-off cock. H. and 
R—Supports. B.—Base. O.—Outlet. S.—Glass tube 
through which the formalin drops to tank below---- 
Garbage can suspended to wire, used in fumigating with 
tobacco. stems) ----.------4.5--2---c-t ene sanse ses 
Female nematode (Heterodera radicicola) magnified 85 
diameters; a, mouth; b, spherical sucking bulb; c, 
ovaries as seen through the body wall; d, anus; e, 
small white spots showing approximately the natural 
size of these worms. They are usually white. It is 
generally not difficult to isolate them in water by 
breaking open the galls containing them. (After 
N. A. Cobb) ------------ 
Male nematode: I, Worm in profile view; II, head of 
the same, more highly magnified; III, middle region 
of the worm, showing blind ends of the sexual 
organs; IV, posterior extremity. The drawings were 
prepared from stained specimens, examined in car- 
bolic acid solution. a, lips; b, cesophageal tube; c, 
median bulb; d, excretory pore; e, spear; f, intes- 
tine; g, blind ends of testicles; h, testicles; i, 
spicula; j, rudimentary bursa; k, anus. (After 
Ne As (Cobb) te eee ie a ee oe 
Galls on cucumber roots produced by nematodes_______- 
Roots of tomato plant completely invaded by gallworms. 
(After George F. Atkinson) ----_-------.---__-_____ 
Galls on lettuce roots caused by nematodes____________. 
White fly (Aleyrodes vaporariorum): a, egg; b, young 
larva; c, pupa, top view; d, pupa, side view; e, 
adult—c, d, e, about 25 times natural size; a, b, still 
more enlarged (a-d, after Morrill, Tech. ‘Bul. Mass. 
Exp: otavs 6, original). 2-5-2. ees eee 
Two nurseries in a four-acre Boston range. Note let- 
tuce seedlings of different sizes--__----------------- 
Nursery in large range near Boston. Head lettuce 
plants: -so-c ne eee abe a eee ee So ceat aed 
Flat of Grand Rapids lettuce seedlings-_-------------__ 
Flat of lettuce plants ready for transplanting into the 
b@dS: gna cexis ete coe es sete as, eoesececsce 
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