Maech 16, 1906.] 



SCIENCE. 



425 



suffocation spots, did not enlarge much, 

 did not contain any organisms, and bore 

 no relation whatever to the genuine bac- 

 terial infection spots which appeared in 

 great numbers some weeks later on these 

 same plants, and passed through the typical 

 stages of the angular leaf-spot. The au- 

 thor has since learned from Mr. W. A. 

 Orton that similar sterile spots occur nat- 

 urally on cottons in the field in rainy sea- 

 sons. Attention was then called to the 

 various mechanical obstacles which the 

 bacteria meet with in the plant, and the 

 methods by which these are overcome, to 

 wit, by growth: (1) through vessels; (2) 

 through parenchymatic tissues by way of 

 the intercellular spaces, with the eventual 

 formation of cavities; and (3) from cell 

 to cell without the primary occupation of 

 the intercellular spaces. The transpiration 

 stream appears to have little to do directly 

 with the movement of bacteria in the stems 

 of diseased plants. It appears to be made 

 out with reasonable certainty that in some 

 cases bacteria pass from cell to cell through 

 pits or thin places without crushing the 

 cell-wall or dissolving any great portion of 

 it. Such would seem to be the manner of 

 movement of Bacillus amylovorus in some 

 tissues of the pear. The writer spoke of 

 the fact that new leaf-spot diseases due to 

 bacteria are constantly turning up, the 

 latest one being a disease of the Gloire de 

 Loraine begonia, cultivated in hothouses 

 for winter blooming. Some observations 

 were also detailed respecting the curious 

 distribution of starch in young potato 

 tubers diseased by Bacterium solanaceariim. 

 This organism, as is well known, has very 

 little diastasic action on potato starch. The 

 irregular distribution of the starch in such 

 tubers seems to point, therefore, not to a 

 solution of starch grains already laid down 

 in the amyliferous tissue, but to the paral- 

 ysis or death (by enzymic action or other- 



wise) of considerable areas of tissue sur- 

 rounding the bacterial foci, so that it is 

 impossible for the plant to lay down starch 

 in such cells. Sections of such tubers from 

 paraffin infiltrated material show the starch- 

 less areas to be roughly proportionate to 

 the size of the central bacterial focus; if 

 this is large, i. e., of some age, there will 

 be a correspondingly large area of the sur- 

 rounding tissue which is destitute of starch 

 grains or which bears them only in oc- 

 casional cells. If the bacterial focus is a 

 small one, the area destitute of starch will 

 be correspondingly reduced in size. In 

 tubers infected after they have reached a 

 greater age the starch grains are present, 

 and even in the center of a bacterial focus 

 remain undissolved, and, so far as can be 

 determined microscopically, are not cor- 

 roded even on their margins by the action - 

 of the organism. 



Report from the Co-mmittee on the College 

 Entrance Option: Presented by Pro- 

 fessor W. F. Ganong, Smith College. 

 A committee of the Society for Plant 

 Morphology and Physiology, the present 

 members of which are Professors W. F. 

 Ganong and F. E. Lloyd, was appointed 

 in 1900 to formulate a college entrance op- 

 tion in botany. The committee has pub- 

 lished three reports, well known to mem- 

 bers ; and the course there formulated, based 

 upon earlier educational reports and the 

 approval of a large number of the prom- 

 inent teachers of botany throughout the 

 country, has been adopted by the college 

 entrance examination board and by a large 

 number of schools. The committee had 

 been continued as a standing committee of 

 the society with instructions to keep the 

 option in touch with educational advance, 

 and from time to time to report such 

 alterations as may seem desirable. In the 

 present report the committee stated that 

 it had been gathering evidence as far as 



