84 



media for a year, this organism again produced the disease when 

 inserted into the leaves and floral organs of health}' plants, and, after 

 a lapse of some months, was again demonstrated to be present in 

 enormous numbers in yellow broken-down bundles in the interior of 



the bulbs. 



The time of first appearance of sj'mptoms in the inoculated leaves 

 varied within wide limits, according to the variety tested and the 

 amount of material used, but nearly all the specimens of Hijacintlius 

 orientaJis which were inoculated showed the disease in three to thirty 

 days in the parts above ground, and 40 of these plants also showed 

 characteristic symptoms in the bulbs at the end of two to five months. 

 In 1898 the conditions toward the end of the experiments were very 

 unfavorable to the progress of the disease, owing to the extreme heat 

 of the summer. In 1899 the experiments were disturbed and broken 

 off too soon. 



The results I have obtained indisputably confirm Dr. Wakker's 

 statements respecting the aetiology of this disease. My studies lead 

 me to accept substantially all of his statements regarding the char- 

 acter and succession of symptoms in this disease and the lesions in 

 the liost plant due to its progress. They seem to show that some 

 varieties are more susceptible than others, e. g.. Czar Peter than 

 white Baron von Tuyll, and Gertrude than Gigantea. They show, 

 as Wakker stated, that daughter bulbs contract the disease from 

 mother Imlbs. They do not clearly establish that the germ has any 

 other host plant or that the parasite can enter through the stomata. 

 They show that it is easy to induce the disease by wounds. Tliey 

 also indicate that bulbs may sometimes become diseased as the result 

 of germs lodged in the flowers, and that bees sometimes visit such 

 flowers. The last two facts point to leaf-eating and nectar-sipping 

 insects as probable carriers of this disease. A priori, there is noth- 

 ing improbable in this view, since two bacterial diseases common in 

 the United States, the cucurbit wilt and the pear blight, are dissemi- 

 nated in this way, the former from germs lodged in the leaf, princi- 

 pally by the bites of leaf -eating beetles, the latter from germs lodged 

 in the nectaries by bees and other insects which visit the flowers for 

 nectar and pollen. It remains, however, for some one in the Nether- 

 lands, where the bulbs are grown in quantity, and where the disease 

 is prevalent, to remove this statement from the domain of likelihood 

 to that of actual fact or to show that it has no real foundation. 



Wakker believed the disease to be often transmitted by the knife, 

 and there is every reason to think his views well founded. In this 

 case the practical deductions are easily made. Knives used on dis- 

 eased plants should not be used on healthy plants until they have 

 been thoroughly disinfected. For this purpose it is only necessary 

 to dip them into boiling water for a few minutes. 



Possibly healthy fields may become infected from the slime of the 

 canals, into which, I am told, diseased bulbs are commonly thrown 



