YELLOW DISEASE OF HYACINTHS. 351 



solution is bleached slowly; resists drying; is not readily destroyed by its own decomposi- 

 tion products ; forms indol sparingly; yellow pigment readily soluble in glycerin, acetone, 

 and aqueous solution of ammonium carbonate; acetone extract destroyed by light and 

 rendered blue-green or purplish by concentrated sulphuric acid; brown stain in hyacinth- 

 broth, and on radish, turnip, etc. ; slight pink stain (trace) in nutrient starch-jelly (made 

 with peptone-water or Uschinsky's solution) with diastase; minimum temperature 4 C., 

 optimum 28 to 30 C., maximum 35 C., thermal death-point 47.5 C. most of the rods in 

 tubes of bouillon are killed by 10 minutes' exposure at 46.5 C. ; destroyed by sunlight. 

 Group No. 211.2322523. 



NEGATIVE. 



Endospores; capsules (?); Gram's stain; gas; acids (from milk, glycerin (?), coconut 

 flesh); assimilation of lactose, maltose, methyl alcohol; growth on agar streaks with 23 

 per cent grape-sugar; anaerobism (no growth in vacuo or gases, nor in closed end of fer- 

 mentation tubes except with impure maltose) ; solubility of yellow pigment in petroleum 

 ether; brown stain (agar, gelatin, peptonized beef -broth); strong odors; growth after 

 exposure to sunlight 30 min., and 45 min. (thin sowings in agar plates); reduction of 

 nitrates to nitrites; growth at 37. 5 C. ; action on starch (nearly) ; growth in media decidedly 

 acid to litmus; action on cell-walls of potato; Cohn's solution? 



Any organism developing endospores readily, producing gas, or growing anaerobically 

 with grape-sugar, or cane-sugar, having a strong diastasic action, e. g., filling the water 

 around potato cylinders in test tubes with a solid yellow slime, tolerating much acid, 

 reddening litmus milk, liquefying gelatin quickly, producing a greenish stain, or forming a 

 white growth on agar or potato, may be set down at once as something else. 



TREATMENT. 



In Holland the growers fight the disease by eradicating the diseased plants as fast as 

 they are discovered. With these they commonly remove a little of the surrounding earth, 

 but of course they can not remove all the infectious bacteria. From blossoming time on, 

 the fields are searched regularly for the presence of this disease. The growers shade their 

 eyes and the plants from the sun with bluish-green umbrellas, and this light enables them 

 to see the disease on the parts above ground readily. This is the correct practice. Those 

 plants which are found to be diseased in the field should be removed immediately and 

 destroyed. They should never be allowed to decay in place, nor, when removed, should 

 they be thrown into the canals, or upon the rubbish heaps. If conveniences are at hand, they 

 may be burned, if not, they may be thrown into glass jars containing dilute, crude sulphuric 

 acid to which more acid is frequently added. The bacterium is very quickly killed by acids, 

 even when dilute. It goes without saying that diseased bulbs should never be planted. 

 If diseased bulbs are used for the production of other bulbs either by notching or by the 

 removal of the plateau, some of the daughter-bulbs are quite certain to contract the disease. 

 If the disease is disseminated by insects, as seems not unlikely, means should be devised for 

 their extermination. This subject deserves very careful inquiry. 



By rubbing the yellow slime over the cut surface of bulbs Wakker secured infection of 

 the vascular bundles of the youngest scales in 14 days, and in those of the older scales a 

 little later. It appears probable, therefore, that the tools used by the gardeners sometimes 

 transmit the disease. Growers may at least assume this to be true and govern themselves 

 accordingly. Knives and other instruments used for cutting diseased bulbs should not be 

 used on healthy bulbs until they have been disinfected, which may be done by soaking them 

 for a short time in 5 per cent carbolic acid, 5 per cent lysol, o. 5 per cent formalin (strong) 

 o.i per cent mercuric chloride, or in boiling water. A very short exposure to boiling water 



