The results of the attempts here described to cultivate the incitant of mosaic disease of tobacco and tomato plants give good reason to suppose that this has been accomplished. The agent in the tissues of affected plants induces the disease not infrequently in a dilution of 1:10,000 but only very rarely at a higher dilution. During its transference from tube to tube of the special medium used in the present study it underwent a dilution far beyond these effective limits—in one experiment to 4 x 10–16. Nevertheless, the material of the remote subplants proved effective in inducing the disease, which appeared as rapidly and in as active a form as if the undiluted inoculum had been employed. Material derived from plants in which mosaic developed as result of inoculation with the culture fluid induced the disease in yet other plants, and from these again the agent could be propagated in vitro, or transfers to other plants could be made. In the course of the experiments a significant fact was noted; namely, that the agent present in remote subplants which can induce the disease was not readily filterable. The nature of the change thus indicated remains to be determined. No formed elements could at any time be distinguished in the medium. The conclusion seems justified that the incitant of mosaic disease of tobacco and tomatoes is a living microbic body which can be cultivated in an artificial medium.
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机译：这里描述的培养烟草和番茄植株花叶病诱因的尝试结果提供了充分的理由来假设已经完成。受影响的植物组织中的活性剂通常不会以1：10,000的稀释度诱发疾病，但很少会以较高的稀释度诱发疾病。在本研究中使用的特殊培养基从管子到另一管子的转移过程中，它的稀释度远远超出了这些有效限度—在一个实验中，稀释度为4 x 10 –16 。然而，事实证明，远距离子植物的材料可以有效地诱发该疾病，这种疾病的出现速度和活性都与使用未稀释接种物一样快。来源于植物的材料，在该植物中接种了培养液后会形成花叶，从而在其他植物中引起该病，并且可以再次从这些植物中体外传播该病原，或者转移到其他植物中。在实验过程中，注意到了一个重要事实。就是说，存在于遥远的子植物中的可诱发该病的病原不易过滤。如此指出的变化性质尚待确定。在任何时候都无法在介质中区分形成的元素。结论似乎是合理的，认为烟草和番茄花叶病的诱因是可以在人工培养基中培养的活的微生物体。
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