33 



June 21. Bulb rotted and gone. Of the six checks one is entirely sound, three 

 are slightly soft-rotted, but with no trace of yellow bundles, and two have entirely 

 decayed. 



Notes on plant No. 85. — One plant of Gigantea. four leaves plunged 8 to 7 cm.; 

 six healthy plants in same pot are held for comparison. 



March 80. No symptoms. 



July 1. The bulb ha.s rotted, and it is too late to determine the cause. The bulbs 

 of all the check plants have also rotted. 



Notea on plant No, ,W.— One plant of Gigantea. five leaves plunged 2 to 7 cm.; 

 three healthy plants in the same pot were held for comparison. 



March 30. No symptoms. 



July 1. Leaves dead. Heart of bulb rotted out. No symptoms of the yellow dis- 

 ease in the scales which remain. The checks are also free from this aisease. One of 

 them has soft-rotted. The centers of the other two are also soft from the presence 

 of the white rot. 



INOCULATIONS OF 1899. 



SERIES 19 (HYACINTHS), 



This experiment, begun February 22, was another attempt to infect 

 through the blossoms. From 4 to 10 flowers were inoculated by put- 

 ting several small drops of the Infectious fluid into the heart of the 

 blossoms by means of a sterile hypodermic syringe. For infection, I 

 made use of slime from an activelj^ motile young bright-yellow cul- 

 ture on coconut. This slime was dissolved by shaking in a small 

 quantity of distilled water. 



The varieties tested were Regulus,,blue Bar&n von Tuyll, w^hite 

 Baron von Tuyll, Gertrude, and Gigantea. 



The experiment was unfortunately interrupted on June 7, at whicli 

 time the bulbs of 8 of the inoculated plants were visibly affected by 

 the j^ellow disease, i. e., about one-third of the wiiole number. About 

 40 ijlants were held as checks, none of which showed any external or 

 internal symptoms of the disease. Regulus was affected to a gi-eater 

 extent than the others, but in all cases the symptoms were slight, and 

 some months more would have been necessai-y for the bulbs to become 

 seriously diseased. 



REMARKS ON PATHOGENESIS. 



Th(^ Inoculation experiments were all made with pure cultures, on 

 sound i)laut.s, in a liothouse where hyacinths had never before been 

 grown, and in a country where tlie disease is not known to occui*. 

 Moreover, none of the several luindred check plants contracted the 

 di.scasc. It is therefore reasonal)ly certain that all of tlie infectious 

 matei-ial was derived fi-om my cultures. The i)athogenic natui-e of 

 these cultures is rendered certain (1) because tlie symptoms always 

 began in that part of the plant wliich was iiuK'ulated and i)rocee(k'd 

 downwai-d, the bulb l)eiug the last part, to show the di.sease; (2) l)ecause 

 the organism occurring so abundantly in the yellow bundles of the 

 bulbs was demonstrated by cultures therefrom and by microscopic 

 examinations to be tlie same as tliat Inserted into tlie leaves and 

 scapes months earlier; {:)) because, after cultivation on artificial 

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