Repository: UIHistories Project: Board of Trustees Minutes - 1886 [PAGE 305]

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299 In Iowa, to the westward, it seems not to have occurred spontaneously that year, the only appearance of it noted by Prof. Osborn, of the Agricultural College of that State, being the result of an experiment, the material for which I furnished him from Normal. It prevailed there the year following, and wherever it once occurred it continued throughout the season, as far as our observations went. The facts clearly and positively negatived the supposition that there was anything in the weather or local conditions to explain either the presence or the absence of the disease, and all bore out the hypothesis of a gradual progress from the east westward. The same phenomena of irregular local distribution were manifest the next year (1884). In certain large fields almost daily observed, it was impossible to find a single diseased larva at a time when, half a mile away, the cabbage worms of small patches had been almost wholly destroyed, their blackened bodies, or the shriveled remnants of the same, being scattered everywhere on the leaves. From the foregoing the conclusion is unavoidable that all the circumstances of the natural occurrence and spread of the disease are consistent with the hypothesis of its contagious character, and wholly inconsistent with any other. Two attempts were made to convey the contagion by means of diseased larvae to localities not previously reached by it, one lot being sent October 3 to Dr. Boardman, at Elmira, and one to Prof. Osborn, at Ames, Iowa. The experiment of Dr. Boardman was not wholly satisfactory, for the reason that through an unfortunate delay of the package the worms which I sent him did not arrive until October 22, at which time the disease had appeared spontaneously, in a small way, in his vicinity. Nevertheless he selected, October 23, two lots of twenty-five worms each, all perfectly healthy to appearance, fed them regularly, but exposed all of them to the contagion by enclosing them in two boxes with the dead and sick caterpillars which I had sent him. At the same time he secured ten healthy larvae in a box by themselves and kept them free from infection. The latter lot all pupated without accident, but were not followed further. The first two lots commenced to show symptoms of disease on the fifth day, and by the eighth day all of both lots were dead except three, only one of which finally reached pupation. Even this pupa, in fact, afterwards died and decayed. The material sent* Professor Osborn, of Iowa, including dead and dying worms, and a mounted slide of the micrococci, arrived October 5, and two cabbage heads were at once infected. On the 7th one of the worms "had evidently succumbed to the disease." The gathering of the cabbages under observation during the temporary absence of Professor Osborn, necessarily interfered with the further progress of the experiment but he collected such worms as he could from the stumps and fed them in confinement. A number of these larvae died, and December 28 he wrote me that he had "found micrococci in a number of sick and dead cabbage worms, which must certainly have taken the disease from the ones sent." Although these experiments, taken alone, could scarcely be regarded as conclusive as to the contagious character of flacherie,