The MicROscorE. 329 



up into granules of much smaller size. The mass continues to shrink 

 and becomes tinted with red. From this time, on, the change does 

 not appear to be always the same. Sometimes the shrunken mass 

 seems tough, and remains like a lump in the middle of the cell. In 

 other cases, it breaks up into granular debris immersed in water. 

 If starch grains existed, they share the fate of the other material 

 and are decomposed. At length the substance passes into what 

 seems to be an emulsion of oily matter in water. The spherical par- 

 ticles are dark red and usually exhibit Brownian or molecular motion. 

 In certain cells minute starch grains, of uniform size and shape, like 

 little double-convex lenses, occur in great numbers and oscillate rap- 

 idly in the watery cell-fluids. These may be easily mistaken for 

 microbes, but iodine stains them blue. They have been observed 

 only near the borders of the diseased areas, within the parts which 

 have turned red. Finally, little or nothing remains within the 

 inclosure of the cells; the surfaces of the wall, however, usually 

 show what seems to be a granular or dirty deposit clinging to them. 

 The cellulose of the cell-walls is stained beyond the area penetrated 

 by the microbes. The liquid itself in the diseased cells is red, col- 

 ored thiis by some soluble substance, perhaps a compound of tannic 

 acid. 



No attempts have been made to ascertain the chemical changes 

 that take place either in the cultures or in the plants; but it is evi- 

 dent fi-om what has been said that the injuries are chemical rather 

 than mechanical. As before indicated, the effect is, at first, at least 

 purely local. It seems, however, quite probable that cells adjoining 

 the invaded ones sometimes suffer from the absorption of the liquid 

 only of the diseased parts. It indeed may be true that the proto 

 plasm which shrinks into a lump and remains unchanged otherwise in 

 the cell is killed by the poisoned liquid, and not by the direct action 

 of the microbes. The latter have not been observed in such cells. 

 The red coloring-matter is not directly elaborated by the organisms, 

 but results from the chemical decompositions of the cell- contents. 

 The bacteria themselves are white, and do neither absorb nor excrete 

 the red stain. No culture fluid tried is changed in color by them. 



The question is sure to be asked, " What are you going to do 

 about it?" The so-called practical man is very apt to say: "I care 

 nothing about the cause. Tell me the cure." It is not always easy 

 to say how an enemy can be safely met when he is seen: but it is 

 true that a known foe is himself more exposed than one who fights 

 under cover. The knowledge of the cause mav lead to the cure. 



