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Show 18 Utah Academy of Sciences, Arts and Letters, [Vol. XV, of the tobacco mosaic virus no. 1, of the tomato mosaic virus, and of the systemic virus. Series of plants of each species used in the host range studies were inoculated with each of the three viruses for comparative purposes. The symptoms of the tobacco mosaic virus and the tomato mosaic virus a.ppeared to be identical on all hosts tested. The systemic virus developed the same symptoms on the same hosts as the tomato mosaic virus and the tobacco mosaic virus no. 1. with the exception of D. meteloides-the host on which the systemic virus was developed-and D. metel-a closely related host. On these two hosts the systemic virus produces a systemic mottling which mayor may not be associated with occasional small and often inconspicuous necrotic spots whereas the tobacco and tomato viruses produce the character istic streak. Thermal inactivation. Using standard technique, the tobacco mosaic virus no. 1, the tomato mosaic virus, and the systemic virus were all found to have the same thermal inactivation-90° C. for 10 minutes. Temperature treatments below 900 did not appear to affect the systemic virus in any way. Longevity. The tobacco mosaic virus, the tomato mosaic virus, and the systemic virus were separately inoculated on young healthy tomato plants and the systemic virus on D. meteloides plants. As soon as the symptoms were well developed the plants were dried between paper towels in a her barium press and stored in coin nvelopes, January 5, 1936. Samples are being tested at intervals and at this writing (October, 1937) the virus in all the dried tissues is virulent and is retaining its identity. Longevity studies in vitro were started January, 1937. Samples of plant The stored extract were placed in glass vials and kept at room temperature. juices are being inoculated on plants at intervals to test the viability of the viruses. The juices are still infectious, and the systemic virus has retained its identity. Tolerance to lethal chemicals. Freshly extracted juice of plants infected separately with the three viruses were treated with nitric acid, ethyl alcohol, formaldehyde, a.nd mercury bichloride. Samples of the extracts in lots of 5 c. c. each were treated with varied amounts of the chemicals added directly to the plant juice. The viruses were very resistant to the treatments, and no differentiation was found on the basis of their tolerance. The three viruses tolerated 2 c. c. of concentrated nitric acid to 500 c. c. of extract, 3 c. c. of 37 percent formaldehyde to 100 c. c. of plant extract, 40 c. c. of 98 percent alcohol to 100 c. c. of extract, and 1 gram of mercury bichloride to 1000 c. c. of extract for two hours. Interaction of the tobacco mosaic virus and the systematic virus when brought together in plant tissue Tobacco mosaic virus no. 1 and the systemic virus were brought together in the same tissue to determine whether the systemic virus was a contaminant, a part of a virus complex, or a modified form of the tobacco mosaic virus. Effect of inoculating the systemic virus on Datura meteloides plants infected with tobacco mosaic virus no. 1. Twenty D. meteloides plants stand were inoculated with the tobacco mosaic virus no. 1 and allowed to until the progress of the streaking had subsided and secondary shoots had The secondary shoots were then inoculated with the to develop. begun sec systemic virus. Systemic symptoms developed directly on the inoculated that necrotic the of amount noticeable spotting ondary shoots without any inocula uniformly precedes the development of systemic symptoms following . Furthermore, when the lateral tions with the tobacco mosaic virus no. 1. shoots were inoculated with the systemic virus, the symptoms appeared simul taneously over the entire plant. but when the. virus developed from the tobacco . w . • .. .. . .. "'''' ;..; . .. :'"i,) .... ttl . $ """, (.. .... "'''''\. ... " • • '," < --------------- |
