Tub Microscope. 3'i-i 



stimulus to the studios upon the formei* kind of structures. There 

 are hundreds and thousands] of active workers whose professional 

 business it is to deal with diseases of animals and man, and hundreds 

 of special schools where instruction is directly imparted to students 

 uj)on their diseases; but the professional vegetable pathologists are 

 yet to be evolved, to say nothing of special schools for their training. 

 Yet the time cannot be far distant when critical investigations will 

 be made upon vegetable structures for the very purpose of helping 

 towards the solution of the problems presented in animal pathology. 

 This has been recognized by Sir James Paget, whose paper upon the 

 subject is interesting reading. As a contribution to the general doc- 

 trine of "disease germs," as well as for the intrinsic importance of 

 the new results herewith presented, this paper is respectfully sub- 

 mitted. 



During several years, complaints have been made by those who 

 grow crops of broom-corn and sorghum (Sorghum vulgare) of an 

 injury especially evident upon young plants, but also upon those of 

 any age, whereby great losses have occurred. Sometimes the unwel- 

 come appearances of disease are confined to definite but usually 

 irregular areas, and often within these areas the entire crop is 

 destroyed. In other cases, the diseased plants, in greater or less 

 numbers, and in various conditions of injury, are distributed through- 

 out the field, smaller in size than the healthy ones, if any, and of a 

 general sickly appearance. The lower leaves of the affected plants 

 gradually die, but are first spotted and splashed with crimson-red, 

 in all sizes and shapes. This conspicuous coloring is more par- 

 ticularly observed iipon the upper portions of the leaf- sheathes 

 which invest the stem, and, to a less extent, along the mid-veins of 

 the leaves. The stems themselves are not commonly damaged 

 locally in a serious manner. If the stalks live to develop the brush 

 or seed panicle, the peduncles or wiry stems of the latter are often 

 badly scarred with irregular reddish patches. These may often be 

 seen in manufactured brooms. 



Upon examining the roots, many of them are found dead. The 

 affected plants are easily pulled up, often yielding to very slight 

 force, while their healthy neighbors resist a vigorous pull. The 

 oldest roots die first, and, as others are gradually emitted from the 

 lower part of the stem in successive circles, in the well-known order 

 with these plants, they become successively diseased and die, so that 

 only the youngest, or those emerging highest up on the stem, are 

 still alive. There are no abrasions of the surface. As far as can be 



