Mat 20, 1910] 



SCIENCE 



793 



inoculations were claimed. In 1891-92 Macehiatti 

 published papers on tlie disease, confirming the 

 views of Cuboni and claiming successful inocula- 

 tions. In 1894 Beyer and Lambert, in France, 

 studied a blight of mulberries, obtained inocula- 

 tions from cultures, and named the organism 

 Bacterium mori, but did not describe it. In 1897 

 Peglion confirmed Maechiatti's views, obtained 

 infections on leaves and shoots in three days' 

 time, and stated the organism to be yellow and 

 a liquefier of gelatin. Possibly he was working 

 with mixed cultures. 



In 1905 the writer made isolations from blight- 

 ing mulberry leaves, and, influenced by the Italian 

 work, paid attention only to such poured-plate 

 colonies as were distinctly yellow. Two yellow 

 forms were isolated and thorough inoculations 

 were made on growing leaves and shoots of mul- 

 berries, but, contrary to expectation, no trace of 

 infections was obtained. The diseased material 

 came from Georgia. 



In 1908 plates made from Gteorgia material 

 showed the bulk of the bacteria in the freshly 

 blighting stems to be a white species. With this 

 white organism numerous successful infections 

 were obtained on two varieties of mulberry, on 

 both leaves and stems. With pure cultures plated 

 from such blighting shoots, many additional in- 

 fections were obtained. Independently at about 

 the same time two of my co-workers obtained 

 confirmatory results with the same white organ- 

 ism; (1) isolations and successful inoculations 

 on the Pacific slope by Mr. P. J. O'Gara (oral 

 communication); (2) isolations and successful 

 inoculations in Arkansas by Mr. James Birch 

 Rorer (oral communication). Typical-looking 

 cultures were received from both men and with 

 the Arkansas organism successful inoculations 

 were made in a Department of Agriculture hot- 

 house under my direction and also by Mr. Rorer 

 himself. There is, therefore, no doubt whatever 

 as to the infectious nature of the white organism. 

 Whether the Italians who have secured infections 

 inoculated with mixed cultures, one constituent 

 of which was this white organism, or whether 

 there is also a yellow organism {Baoillus Cuboni- 

 anus Macch. ) capable of causing a bacterial 

 blight of mulberry, must be left an open question. 

 If the latter supposition be true then Ouhonianus 

 is perhaps the proper specific name for the yellow 

 organism. 



Inasmuch as Boyer and Lambert obtained in- 

 fections with their Bacterium mori, and have not 

 made any incorrect statements respecting its 



character, I have adopted their name for the 

 white organism, with the following emended 

 characterization : 



Bacterium mori B. & L. emend. Schizomyoete 

 causing a blight of leaves and young shoots of 

 the mulberry. Spots at first water-soaked, then, 

 sunken and black; foliage more or less distorted; 

 shoots soon show sunken, black stripes and dead 

 terminal portions. Action of disease rather 

 prompt. In very young shoots all the tissues are 

 involved— wood, pith and bark being infested by 

 the bacteria. In older shoots the bacteria are 

 confined mostly to the xylem and especially to 

 the vessels, where tyloses are produced, as a result 

 of the stimulus of the organism. 



The organism is motile by means of a polar 

 flagellum, sometimes two are present. It is 

 actively motile when examined in a hanging drop 

 made from a three-day agar culture. It occurs 

 as single rods, pairs and short or long chains. 

 The ends of the j-od are rounded and the limits 

 of size are 1.8 to 4.5 /t X 0.9 to 1.3 m- Most are 

 3.6 fiX 1-2 fi. No spores have been observed. 

 Pseudozoogloeae occur, and involution forms were 

 seen in beef-bouillon containing 6 per cent, sodium 

 chloride. It stains readily with carbolfuchsin, 

 but not by gram. 



Colonies on + 15 Agar at 23° (7.— White, slow- 

 growing, round, smooth, flat, edge entire becoming 

 undulate after some days, internal structure re- 

 ticulate or striate. 



Young Agar Streaks.— Qio-wth moderate, spread- 

 ing, flat, dull, smooth, becoming finely granular, 

 translucent, slimy, odorless, white, medium not 

 stained. 



Agar Stabs.— Best growth at top. 



Potato.— Growth moderate, spreading, flat, 

 glistening, smooth, white to dirty white, slimy 

 and medium grayed, only slight action on the 

 starch. 



Laiffler's Blood 8erum.—Stvea.k spreading, flat, 

 glistening, smooth, white. No change in color of 

 substratum or liquefaction (two months). 



Surface Colonies on + 10 Nutrient Gelatin. — 

 Flat, slow-growing, round to irregular, with 

 lobate-erose margins. 



Gelatin Stabs. — Best growth at top, line of stab 

 filiform, no stain, no liquefaction. 



Peptonized Beef-broth (+ i5).— Produces a 

 pellicle, which breaks into fragments readily and 

 sinks, forming a flocculent fluid; strong turbid 

 clouding (clear after three months). Growth 

 always best at the top, no distinct odor. 



MiJfc.— Coagulation absent, fluid becomes clear 



