190 Investigations in Plant Pathology 



of Ferdinand Hueppe, was washed out in 60 per cent alcohol and 

 mounted in glycerine. Smith had noted that Hueppe had said 

 that glycerine could be used only with the brown dyes, since it 

 extracts other anihn colors rather quickly. Five differing sets of 

 stained sections were examined that first day, but still no trace of 

 mycelium was found. While certam darkly stained rod-shaped 

 particles in the nuclei resembled bacilli. Smith believed these were 

 only parts of nuclear filament. A section stained five days in a 

 watery solution of Eosine, washed in distilled water, and examined, 

 again shovv'ed "no mycelium and nothing suggestive of bacteria." 

 Then were tried three sections stained five days in a concentrated 

 alcoholic solution of methyl violet diluted with distilled water. 



Sections through the black pith of a yearling branch affected by 

 yellows were prepared, and stained, five sections with fuchsin and 

 six sections with iodine diluted; then tangential sections through 

 the inner bark of the same branch with fuchsin and iodine, gentian 

 violet, magdala, and safranin. March 7 found Smith studying the 

 gum pockets in diseased wood. J. H. Wakker had published a 

 method by which he had demonstrated gum in living cells, and 

 this Smith had copied into his notes. In an 1882 edition of a 

 book, Practical Microscopy, published in England, Smith found a 

 formula for picro-carmin staining of vegetable tissue. With slight 

 modifications the formula could be applied to wood sections. He 

 tried staining the gum pockets of diseased peach wood with 

 picro-carmin. Section were stained also with fuchsin, methyl 

 violet, gentian violet, iodine, and bismarck brown. March 10 he 

 thought he had a discovery. Cross sections showed " many small 

 dark bodies in interstices of tissue, but I," Smith wrote, "' cannot 

 determine them to be bacteria. They disappeared after washing 

 in acid alcohol, though much color still remained. These bodies 

 are smaller than pear blight, longer than broad, and more like 

 bacteria than any bodies yet seen." He manipulated the micro- 

 scopes with all the skill at his command, repeated the experiment, 

 but his examination ended again with " no trace of the bacteria- 

 like bodies." When he cut through the brown spot of the bark, 

 some mycelial fragments seemed to be in evidence, " some distinct 

 from tissue, others between cell walls." So he put these aside for 

 further study. March 11, however, his entry was concluded with 

 "" Uniform transparent brown stain. No trace of bacteria and 

 mycelium indefinite." March 14, he concluded that certain of the 



