26 



j^^s^i^/. —Characteristic symptoms of the yellow disease were visible 

 on each of the iiiocvilated leaves as early as February 14. At first the 

 disease progressed much more rapidly than on any other variety. 

 Later its spread was slow. The stripes in the inoculated leaves 

 extended downward slowly untiV the end of March, at which date 

 there were symptoms on no otlier leaves. About this time both of 

 the inoculated plants and the two check plants were attacked and 

 destroyed b}^ the rapid soft white rot. 



SERIES 9 (hyacinths). 



The ninth series of inoculations was made February 11 from the same 

 culture and in tlie same manner as the preceding, i. e., 0.3 cc. of the 

 cloudy fluid was injected into each leaf. For this experiment I 

 selected two healthy plants of a single-flowered, j)ale-rose variety 

 known as Gigantea. Six plants of the same varietj^ in the same pot 

 were held as checks. The plants were in full bloom. Each i^lant 

 had four to five leaves, three on each plant being inoculated near 

 the apex. At this time the leaves were 9 to 11 cm. long. 



Result. — On February 17 there were no symptoms on either plant. 

 By March 1 there were pronounced stripes on four of the six inocu- 

 lated leaves. The other two leaves (seventeenth day) showed no symp- 

 toms. These stripes were 2 to 3 mm. wide and 6 cm. long, extending 

 down the middle of the leaf. The older portions of these stripes were 

 dull yellow and semi-transparent, with pale brown bundles. Above and 

 below this portion the striping continued in the form of water-soaked 

 spots. To either side of these narrow stripes the leaf was healthy. 

 The appearance of one inoculated leaf from each plant (March 5) is 

 shown in PL I, figs. 3 and 4. Later, both of these plants Avere spoiled 

 by the rapid soft white rot. None of the uninoculated leaves ever 

 showed any symptoms of the yellow disease. Two of the check plants 

 developed the rapid soft rot and were dug out soon after the experi- 

 ment began. In both the rot began in the blossoms, and in one it was 

 still confined to a single flower and a small portion of the adjacent 

 scape when discovered. The other four check plants were dug and 

 examined June 17. All were soft-rotted at the heart, but in the scales 

 which remained in condition to be examined there were no yellow 

 bundles. 



SERIES 10 (hyacinths). 



The tenth series of inoculations was made February 11 from the 

 same culture as the preceding. For this experiment another pot of 

 Gertrude was selected. The plants were in full bloom and very 

 healthy. Four were inoculated and four others in the same pot were 

 held for comparison. Each of the plants bore eight to ten leaves. 

 Two were inoculated in the apical portion of the leaves (three leaves 

 on each plant) by means of a hypodermic syringe, 0.3 cc. of the cul- 

 ture being put into each leaf. The other two were inoculated in the 

 same way in the scape, just under the truss of flowers, several punc- 



