358 BACTERIAL DISEASES OF PLANTS 



of blighting shoots and the harder basal part. Is the pith in- 

 volved? Are the medullary rays occupied? Where are the 

 bacteria located outside of vessels, i.e., within cells or between 

 them? In the leaves do the bacteria make special use of the 

 vessels? Is the parenchymatic tissue killed in advance of its 

 occupation? Parts long diseased are hard to embed on account 

 of entrance of air; you will, therefore, collect unshriveled soft 

 stems and leaves, and fix without delay, using the air pump. 



Variability. — ^Little is known. 



Transmission. — ^Nothing is known respecting carriers of the 

 bacteria or the natural methods of infection. The organism 

 enters readily through wounds and probably also through stom- 

 ata and lenticels. Settle the latter by experiments, if you have 

 the opportunity. As in fire-blight of the pear, the copious 

 ooze of bacteria to the surface of the blighting leaves and 

 shoots affords abundant material for infecting other parts of the 

 same tree and for transmission to neighboring trees, and it is 

 advisable, therefore, to remove all blighting branches promptly. 



LITERATURE 



For earlier notes by the writer read: Science, N. S., Vol. 

 XXXI, May, 1910, p. 7 92; and Phytopathology, Vol.4, 1914, p. 34. 



For Macchiatti's paper consult Malpighia, Anno. V. Fasc. 

 VII-XII, Genoa, 1892, pp. 299-303. 



For Boyer and Lambert's paper consult Cornptes Rendus 

 hebd. des Se de. VAcad. des Sci., Paris. Tome CXVII, Aug. 21, 

 1893; pp. 342-343. 



Read Doidge's paper "The South African Mulberry Blight" 

 (The Annals of Applied Biology, July, 1915, p. 113). 



See also ''Etudes sur les maladies du Murier en 1913" by G. 

 Arnaud and Ch. Secretain, Annales du Service des Epiphyties. 

 Tome II, Memoires et Rapports, Ministere de L' Agriculture, 

 Paris. Librairie Lhomme, 1915, pp. 233-249, 11 text figs. 



Consult also "Bacteria in Relation to Plant Diseases," Vol. 

 II, 1911, Figs. 3 and 30. 



