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Caption: Board of Trustees Minutes - 1880
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73 MICROSCOPICAL CHARACTERS.. J Eig. 1. Cross section of healthy bark taken ?• e * 1 August 1. The cells are full of starch. Magni- spermatid 01 SOme t u n g U S , SHOWS fled 125 times, linear. t h e w a n t ftt t h e t i m e 0 f a p r 0 p e r -n. -, ,, ,. „, ,., , , +r The organism to which we attribute the death of our fruit trees is so minute that a magnifying power of two hundred times across is necessary to see it at all, and one thousand diameters is required for careful study. Only the objective^ of sharpest and finest definition give satisfactory results. My own mistake, recorded in the Transactions of the Illinois Horticultural Society, 1877, p. 114, by which these minute bodies were equivocally referred to the glass. The wide-angled objectives of recent manufacture are expensive instruments, but are immensely superior for this kind of work. During the course of the development of the minute creature of which we write, it assumes various shapes, and those of different forms may ordinarily be seen together in the field of the microscope. The most characteristic form, and that most abundantly seen, consists of two oblong joints with obtusely rounded ends, attached close together by a broad base, end to end. Their transverse diameter is about one-thousandth of a millimeter (.0000394 inch), and the l e n g t h Of t h e t w o j o i n t s IS t h r e e - F i g . 2 . Cross section of diseased bark from t h o u s a n d t h s of a m i l l i m e t e r same tree, at same time as Fig. 1. Magnified (000118 inch). They are com- m t i m e s ' paratively thicker and shorter than Bacterium tenno, so common in putrifying substances. Their motions are less rapid. They slide forward with a slightly undulating motion, they turn over and on end, but never glide with rapidity across the field. It is exceedingly difficult to determine specifically these minute creatures by size and coco form, or what are termed morphological charBV acteristics alone. This one appears to me distinct from any that have been described, but I do not undertake at present to decide this question. It is quite possible the active atom, which we find in the diseased tissues, is iden- Fig. 3. Bacteria^ causing tical with a common, omnivorous little agent,* trees." MagnmedToootfmes? which converts sugar, amylaceous matter, lactic, l i n e a r *Vibro butyrique, Pasteur. Bacillus believed to be identical. amylobacter, Van Tieghem. These are now
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