. DISEASES OF PLANTS. 897 



the potato well-detiiied cavities arise in the vicinity of the vascular 

 liny, which are tilled with loose starch grains, remnants (•(' cells, and 

 bacteria. 



The behavior of the bacillus in bouillon and peptone cultures, milk, 

 litmus milk, gelatin, agar, potato cultures, and fermentation tubes is 

 given in detail. In none of the cultures was there any gas produced, 

 and the bacillus seems to be strictly ai*robic. Xo acid reaction could 

 be detected in any stage of the culture, while, on the contrary, the 

 organism is a very vigorous alkali producer. 



The thermal death point of the organism is determined at about 52'=' 

 C, 10 minutes' exposure. It grows well in a thermostat at 37'-^, which 

 is slightly higher than the outside summer temperatures. The min- 

 imum temperature for growth seems to be about 13^, but the tempera- 

 ture at which the organism is destroyed by cold was not ascertained; 

 temperatures of —77° C. for 20 minutes failing to kill all the germs. The 

 bacillus readily takes the various anilin stains, and it forms a rather 

 characteristic brown pigment in the host plants and in culture media 

 containing grape, fruit, or cane sugar. 



The host plants for this disease are, as has already been stated, the 

 tomato, potato, and eggplant, but experiments show that it will also 

 affect many other solaiiaceous plants. 



Little is known about the geograpiiical distribution of this disease, 

 but it is known to occur in Mississippi and Alabama, along the coast 

 in the vicinity of Charleston, South Carolina, and near Washington, 

 District of Columbia. It probably exists in many i»lace and is con 

 founded with other diseases. 



Investigations were conducted to ascertain the natural methods of 

 infection, and it was found that the Colorado i^otato beetle would very 

 readily carry the disease from one plant to another, and it is prob 

 a])le that insect enemies are largely responsible for the spread of the 

 disease. 



As preventive measures, the destruction of all leaf eating and leaf- 

 puncturing insects is the first thing to be considered. Harly and com- 

 plete removal of diseased vines, and in the case of the potato the 

 prompt digging of tubers and their immediate use or storage in a cool 

 dry place; rotation of crops; and selection of seed and tubers from 

 plants grown where the disease is not i)revalent are other suggestions 

 of possil)le value in i)reventing the spread of this disease. 



In conclusion, the author draws up contrasting characters between 

 Bacillus tracheiphilus (the cause of the cucurbit wilt), Kramer's bacillus, 

 and the one under consideration. 



Spraying experiments, J. CBAia ((Vf/ffl^/^f IJ.cptl. Farms A'///. AS.9.7, 

 j>l). 11G-12;J). — A report is given of cooperative «'\i>criments on the use 

 of Bordeaux mixture to which I'aris green is added for the prevention 

 of various apple diseases. The formula used was copper sulphate I 

 lbs., lime 4 ll)s., Paris green 4 oz.. and water ."iO gal. In nearly every 

 175«;i_Xo. 10 o 



