152 Butler . — A Study on Gummosis of Primus and Citrus , with 
Ruhland, W. : Zur Physiologie der Gummibildung bei den Amygdalaceen. Ber. d. Deutsch. Bot. 
Ges., vol. xxv, 1907, pp. 302-15. 
Savastano, L. : Gommose caulinaire et radicale dans les Aurantiacees, les Amygdalees, le Figuier, 
l’Olivier, et noircissement du Noyer. Comptes Rendus, vol. xcix, 1884, pp. 987-90. 
: Conclusioni cliniche sulla gommosi degli agrumi. Boll, arboricoltura italiana, 
vol. v, 1909. 
: Della cura della gommosi e carie degli agrumi. Atti Comizio Agrario di Napoli, 
vol. iv, 1887. 
: Della gommosi polvinare del pesco. Boll, arboricultura italiana, vol. iii, 1907, 
pp. 78-9. 
: Esperimenti sui rapporti tra i fatti traumatici e la gommosi. Nuovo Giorn. bot. 
it., vol. xix, 1887, pp. 101-3. 
— : I fatti traumatici nella gommosa degli agrumi ed amigdalee e nel nerume del noce. 
Sc. Sup. Portici, vol. iv, 1885. 
: Un altro fatto traumatico provocante la gommosi ed d il marciume negli agrumi. 
Boll, arboricoltura italiana, vol. iii, 1907, pp. 36-9. 
: Un rimedio supplementare alia gommosi degli agrumi. Boll, arboricoltura 
italiana, vol. i, 1905, pp. 59-61. 
Selby, A. D. : Some Diseases of Orchard and Garden Fruits. Ohio Agr. Expt. Sta., Bull, lxxix, 
1897, pp. 121-2. 
Smith, R. E., and Butler, O. : Gum Disease of Citrus Trees in California. California Agr. Expt. 
Sta., Bull, cc, 1908, pp. 235-72. 
Sorauer, P. : Einige Beobachtungen iiber Gummibildung. Landwirt. Versuchsstationen, vol. xv, 
1872, pp. 454-65. 
: Handbuch der Pflanzenkrankheiten, vol. i, 1909, pp. 693-701. 
: Untersuchungen iiber Gummifluss und Frostwirkungen bei Kirschbaumen. Landwirt. 
Jahrb., xxxix, 1910, pp. 259-98. 
Swingle, W. T., and Webber, H. J. : The Principal Diseases of Citrus Fruits in Florida. U.S. 
Dept. Agr., Div. Veg. Phys. and Path., Bull, viii, 1896, pp. 28-33. 
Tr&CUL, A. : Maladie de la gomme chez les Cerisiers, les Pruniers, les Abricotiers, les Amandiers. 
Comptes Rendus, vol. li, i860, pp. 621-4. 
: Production de la gomme chez le Cerisier, le Prunier, 1 ’Amandier, l’Abricotier et le 
Pecher. L’lnstitut, vol. xxx, 1862, pp. 241-4. 
Wiesner, J. : Ueber ein Ferment, welches in der Pflanze die Umwandlung der Cellulose in Gummi 
und Schleim bewirkt. Bot. Zeit., vol. xliii, 1885, pp. 577-83. 
Wigand, A. : Ueber die Desorganisation der Pflanzenzelle, insbesondere iiber die physiol. Bedeutung 
von Gummi und Harz. Pringsheim’s Jahrb., vol. iii, 1863, pp. 115-82. 
Zur Beschrankung des Gummiflusses bei Steinobstbaumen. Zeitschr. fiir Pflanzenkrankheiten, 
vol. vi, 1896, pp. 58-9. 
DESCRIPTION OF PLATES VII-X. 
Illustrating Dr. O. Butler’s paper on Gummosis. 
PLATE VII. 
Upper figure. Citrus Linmium. Cultivated variety affected by gummosis, environs of Whittier, 
Los Angeles County, California. 
Lower figure. Same tree as in upper right-hand figure, Plate VIII, showing marked loss in 
vigour and development of chlorosis due to squamosis on limbs. 
PLATE VIII. 
Upper left-hand figure. Prunus avium. Cultivated variety. Limb on right washed with 
sulphuric acid diluted one-half with water over a small oblong area near origin, and showing 
gummous exudation twenty-two days after treatment. 
