E. S. Salmon and H. Wormald 267 



" Blatter kleiner, Fruchtstande etwa um die Halfte kvirzer, nur 1-1,5 cm. 

 lang. Schuppen zmn grossten Theile zugespitzt, ctwas behaart, an dor 

 Spitze roth werdend. — Galizien." (Ascherson u. Graebner, Hyn. d. mittel- 

 eur. Fl. IV. 597 (1908-13)^) 



Summary. 



1. The wild species H. Lupulus is composed of a number of forms 

 with distinctive morphological and physiological characters. 



2. Forms similar morphologically (for the characters taken) possess 

 distinctive physiological characters (e.g., immunity from, or degrees of 

 susceptibility to, mildew). 



EXPLANATION OF PLATE XXV. 



Fig. 1. Laterals of a seedling (of the wild hop) very susceptible to mildew ; the inflor- 

 escences have been arrested in development. 



Fig. 2. Intertwined laterals of two adjacent hop plants one susceptible to, the other 

 immune from, mildew (see p. 260). 



BIBLIOGRAPHY. 



\. Salmon, E. S., and Wormald, H. '■'■ Humuhis americanuSj Nutt." Journ. oj 

 Botany, 1915, pp. 132—135. 



2. Wormald, H. "Variation in the Male Hoj), Ilumulus Lupulus L." Joinm. 



Agric. Science, Vol. vil. pp. 175 — 196 (1915). 



3. Braungart, R. Der Hopfen (1901). 



4. Salmon, E. S. "On Forms of the Hop (77. Lupulus L.) resi.stant to Mildew 



{S. Hurauli, (D.C.) Burr.)." Journ. Agric. Science, Vol. viil pp. 455 — 460 

 (1917). 

 5. . Idem II. Journ. Genetic.^, Vol. viii. No. 2, pp. 83—91 (1919). 



6. . Idem III. Aiinals of Applied Biology, Vol. v. 252—260 (1919). 



7. . Idem IV. L.c. Vol. vl pp. 293—310 (1920). 



8. . " On Erysiphe Graminis D.C, and its adaptive parasitism within the 



genus Bromus." Annal. Mycolog. Vol. n. pp. 255—267, 307—343 (1904). 



9. Vavilov, N. I. " Immunity to Fungous Diseases a.s a physiological test in 



Genetics and Systematics, exemplified in Cereals," Journ. Genetics, Vol. iv. 

 pp. 49—65 (1915). 



10. BiFFEN, R. H. " Mendel's Laws of Inheritance and Wheat Breeding." Journ. 



Agric. Science, Vol i. pp. 40 — 44 (1905), 



11. . "Experiments on the Breeding of Wheats for Engli.sh conditions." 



Journ. Roy. Hort. Soc. Vol. xx.xil. ; Bej^ort Third Lnternat. Conf. (1906) on 

 Genetics, pp. 373—377 (1907). 



1 We are indebted to Mr E. G. Baker for this information. 



