260 Early Studies in Bacterial Plant Diseases 



that the water passes through the bundle and to be more specific the 

 xylem part. ... It is important to make out clearly to what extent the 

 parenchyma is involved where the general wilt begins. 



[April 14] This much seems clear, when the constitution[al} symptoms 

 first begin, i. e. the general wilt of the foliage, the clogging and destruction 

 of tissues is still confined to the inner non-lignified part of the xylem 

 portion of the bundle. 



On February 11, after examining fourteen slides, Smith prepared 

 a memorandum " On Question of Infection of Phloem in Cu- 

 cumber." " Even where nearly all of the vessels in a bundle are 

 full," he noted, " and large cavities have formed in the primary 

 vessel parenchyma, the phloem is uninjured. Slides from two 

 stems. One bundle found with germs in one sieve tube. Six 

 longitudinal radial sections stained in haematoxylin were also 

 examined. No breakdown in phloem." 



April 1, 1894, he spoke before the Biological Society of Wash- 

 ington on " The Length of Vessels in Higher Plants," the same 

 organization before which he had spoken on May 6, 1893, " On 

 the Symbiosis of Stock and Graft: A Digest of Recent Experiments 

 by Strassburger and [Hermann] Voechting." Smith's research 

 memoranda of these years reveal that on points of final study of 

 peach yellows and laboratory examinations of the cucumber germ 

 he reviewed his knowledge and the latest learning of vegetable 

 physiology. Four or five of Strasburger's writings published 1888- 

 1893 were probably acquired at this time. " Books to buy," a 

 small note book, lists several books by Europeans and at least one 

 work on the microtome. 



During April 1894, Smith outlined the following research on 

 the cucumber study: 



Notes (and drawings) on all my cucumber germ slides (parafine 

 sections) for answer to the following questions: (1) Are there any 

 cavities in the phloem? (2) Any bacteria in the phloem.^ (3) What 

 proportion of the xylem vessels are fuU.^ or contain some bacteria? (4) 

 Which vessels fill first after the spirals, i.e. where situated? (5) Where 

 are the cavities in the xylem? (6) Does the primary vessel-parenchyma 

 stain differently from phloem and rest of xylem ? 



By May 5 he had evolved ^* a formula which would not only 



^'■Introduction to bacterial diseases of plants, op. cit., 117, where it is said, 

 "Long since (1894) the writer resorted to methyl violet, preceded by a bath in 

 tannin water to reduce the excessive stain of the host tissues in stems of cucumber 



