Journal of Agricultural Research voi.xx 



Studies on the Life History and Habits of the Beet Leafhopper 



Plates 



42. Eutettix tenella: A. — Adult, light form. B. — Adult, dark form. C. — Adult, 



color gradation between A and B. D. — Nymph with protruding sac of p ag e 

 dryinid parasite 252 



43. Parasites of Eutettix tenella: A. — Pipunculus industrius: Adult, much en- 



larged. B. — Polynema eutettixi: Adult, much enlarged 252 



Hypertrophied Lenticels on the Roots of Conifers and Their 

 Relation to Moisture and Aeration 



Plates 



44. Section through a hypertrophied lenticel on root of Pinus rigida growing 



in swampy situation 266 



45. A. — Hypertrophied lenticels on the basal part of layering stem of Picea 



mariana, which had been covered with sphagnum. B. — Tap root of a 

 Pinus ponderosa transplant, bearing an unusually large number of hyper- 

 trophied lenticels 266 



46. A. — Cross section of the stem through one of the hypertrophied lenticels 



shown in C. B. — Large patches of excrescences upon the tap root near 

 the root crown, on Pinus rigida. C. — Hypertrophied lenticels on root of 

 5-months-old Pinus ponderosa, grown in a loosely stoppered 2-ounce 

 bottle, in tap water which had not been changed since the germination 

 of the seed 265 



Crownwart of Alfalfa Caused by Urophlyctis alfalfae 



Plates 



47. Urophlyctis alfalfae: Drawing of alfalfa plant, showing abundance of crown- 



wart, as found early in May, 1919, in northern California 324 



48. Urophlyctis alfalfae: A-D. — Peripheral portions of actively growing thallus 



of parasite dissected from living host. E. — Nearly mature resting spore 

 viewed from distil side, showing 11 haustoria in zonate arrangement. 

 F. — Mature resting spore viewed from distil pole, showing 13 pits that 

 mark former location of haustoria. G. — Mature resting spore viewed in 

 profile, showing pits in zonate arrangement and light concavity on 

 proximal side of spore 324 



49. Urophlyctis alfalfae: A. — Section of epidermal region of young foliar struc- 



tures, showing young primary turbinate cells ta-tg, the first products of 

 infection, within epidermal cells. B. — Section of young foliar element, 

 showing wall of invaded epidermal cell disrupted and advance of second- 

 ary turbinate cells tbc-tbe into underlying tissue. C. — Section of tur- 

 binate cell, showing 3 evacuated peripheral segments pa-pc. D. — Sec- 

 tion of maturing resting spore, showing 8 nuclei and a central vacuole 

 containing 4 granules staining red. E. — Section of mature resting spore, 

 showing numerous red-staining granules in center and 5 nuclei. F. — 

 Section of maturing resting spore, showing 11 normal nuclei and 4 en- 

 larged nuclei in center, the latter apparently degenerating 324 



50. Urophlyctis alfalfae: Section of diseased bud scale of alfalfa, showing four 



coalescing cavities, in three of which the large primary turbinate cells 



taa, tba, and tc may be distinguished 324 



51. Urophlyctis alfalfae: Section of diseased bud scale attacked by U. alfalfae, 



showing a group of eight well-developed cavities a-h and their relation 



to the host tissue 3 2 4 



