XII 
Journal of Agricultural Research 
Vol. II 
Aroma or Hops: A Study of the Volatile Oil with Relation to the 
Geographical Sources of the Hops 
Page 
Fig. i. Relative ester content of various hop oils. 127 
2. Fractionation curves of hop oils from the crops of 1906. 130 
3. Fractionation curves of hop oils from the crops of 1907. 131 
4. Fractionation curves of hop oils from the crops of 1908. 132 
5. Fractionation curves of hop oils from the crops of 1909. 133 
6. Optical-rotation curves of hop oils from the crops of 1906. 137 
7. Optical-rotation curves of hop oils from the crops of 1907. 138 
8. Optical-rotation curves of hop oils from the crops of 1908. 139 
9. Optical-rotation curves of hop oils from the crops of 1909. 140 
10. Ester-number curves of hop oils from the crops of 1906. 143 
11. Ester-number curves of hop oils from the crops of 1907. 144 
12. Ester-number curves of hop oils from the crops of 1908. 145 
13. Ester-number curves of hop oils from the crops of 1909. 146 
14. Fractionation curves of original and saponified hop oils. 153 
Citrus-Root Nematode 
Fig. 1. Tylenchulus semipeneirans: Mature and half-grown females, with their 
head ends permanently embedded in the feeding root of a Citrus 
tree. This is a plant parasite similar in many ways to the notorious 
gall worm Heterodera radicicola. a, Tail end; b, vulva; c, excretory 
pore; d, e, egg in uterus. 218 
2. Healthy Citrus root magnified 5 diameters. Note the size and form 
of the healthy root endings. Compare with figure 3. 218 
3. Citrus root attacked by the parasitic nematode Tylenchulus semipene - 
trans, magnified 5 diameters. The parasites are shown at a. They 
are shown black, but in reality are yellowish or brownish. 219 
4. Tylenchulus semipeneirans: Lateral view of full-grown male, a,Lip 
region; b, spear; c , 3-bulbed base of spear; d, oesophageal lumen; 
e, median oesophageal bulb;/, nerve ring; g, cardiac oesophageal 
bulb; h , beginning of the intestine; j, large intestinal granule; k y 
small intestinal granule; l, anus; m, spicula; n, excretory pore; o , 
spermatocyte; p f vas deferens; q, spermatozoon. 220 
5. Tylenchulus semipeneirans: Female ready for fertilization, a, Lip 
region; b, guide of spear; c, shaft of spear; d, lumen of oesophagus; e f 
median oesophageal bulb; /, nerve ring; g } cardiac oesophageal bulb; 
h, beginning of intestine; </, ovary; n\ duct of renette; n, excretory 
pore; r, vulva; s, wings of the cuticle; V, deteriorated anus; i, 
terminus. 221 
6. Tylenchulus semipeneirans: Larva, soon after hatching from the egg. 
a, Lip region; b> spear; c, 3-bulbed base of spear; d, lumen of the 
oesophagus; e, median oesophageal bulb; /, nerve ring; g } posterior 
oesophageal bulb; h, beginning of the intestine; j , large intestinal 
granule; k, small intestinal granule; n, excretory pore; i, terminus.. 222 
7. Tylenchulus semipenetrans: Young larva of male undergoing the first 
or second molt, a, Lip region; a', lip region of sloughed skin; 
b, deteriorating spear; 6 / , spear of the sloughed skin; d, lumen of the 
oesophagus; e , median oesophageal bulb;/, nerve ring; g, cardiac 
oesophageal bulb; h } beginning of the intestine; j, large intestinal 
granule; k , small intestinal granule; n, excretory pore; 0, immature 
internal sexual organ; l f developing male sexual opening; i f terminus 
223 
