322 The Microscope. 



mental inertia (if one may so speak) too great for change when once 

 started. As these latter intellects are not to be looked for within 

 the membership of our organization, nothing further need be said 

 here to meet such opposition. To the former, if present, this com- 

 munication may possess something of interest. 



We certainly have some advantages, in investigations of this 

 kind, in dealing with vegetable instead of animal bodies, on account 

 of the comparative simplicity of structure and physiological function 

 in the former. In plants, each cell is, in an important sense, an 

 independent physiological unit. One can cut a section fi'om a living 

 plant, for microscopical examination, and keep it under his eye for 

 hours, while it retains its normal vital condition and activities. There 

 is no nervous system to complicate the pi'oblem, and perhaps lead 

 one to false conclusions, as to the actual cause of the phenomenon 

 presented. In plants, there are no so-called constitutional affecta- 

 tions, like chills and fevers. Disease is always local, at least in 

 origin. If other parts are ever involved in consequence, it is only 

 in a mechanical or physical way, as when, by the Avant of proper 

 root action, the stem and leaves may suffer from the want of water, 

 and not at all through sympathetic communication. Then, again, 

 the structure of vegetable tissues is such that the elements can be 

 much more readily examined l^y themselves. The cells are larger 

 and more distinct, as well as more permanent; the difference between 

 wall and contents is greater, and the entire cell -structure is easier 

 identified and examined. 



To be sure, comparatively little has been done in the investiga- 

 tion of plant diseases due to bacteria, but this is sufficiently 

 explained by the relatively few workers upon this department of 

 plant pathology. While the earliest known disease of this kind 

 upon plants was first announced in our country and to this society, 

 there have been recorded in America, aside from the writings of the 

 author, the results of but one series of careful investigations upon 

 the relations of bacteria to vegetable disease, and these upon the 

 same subject as that first presented, viz: the so-called fire-blight of 

 pear and other pomaceous trees. 



This is by no means for want of opportunity upon the material 

 side. . There certainly are enough plant diseases of the nature in 

 question to furnish abundant chance for investigation. The failure 

 is wholly upon the part of the investigators. Man's body is animal, 

 not vegetable, in make-up. This in itself is sufficient to give extra 



