CEdema of the Tomato. 107 



Portions of the cushions including the external parts were then 

 macerated in sterilized distilled water, and the dilution was farther 

 diluted in the usual way in three tubes of liquid nutrient agar contain- 

 ing tomato plant infusion, Esmarch rolls and cultures in Petrie dishes 

 were made of these, and several different bacteria were isolated. 



In like manner leaves of plants in the later stages of the disease 

 were macerated and carried through dilutions to isolate bacteria. Also 

 tissue from the internal parts of petioles and stems in the later stages 

 of the disease were used for dilution cultures. From several such 

 dilution cultures there were obtained fifteen different species of bacteria 

 which were grown in pure cultures anS used for inoculations. Of 

 these there were three species of Bacillus, three of Micrococcus and 

 the remainder probably species of Bacterium. One Micrococcus and 

 four species of Bacterium were chromogenous forms. The chromo- 

 genous forms and one species of Bacillus {B. figurans) were not con- 

 sidered suspicious, but it was very little additional trouble to carry on 

 cultures of these. 



When the organisms were isolated they were grown in quantity 

 in a liquid culture consisting of equal parts of bouillon and tomato 

 plant infusion. 



Experiment JVb. 6, December 19, 1892. Inoculations were made 

 with liquid cultures of the bacteria as follows: The liquid containing 

 the cultures was gently rubbed between the thumb and finger upon the 

 surface of the stem and leaves. Also with a needle abrasions were 

 made of the surface tissue of petioles and stems introducing in this 

 manner into the superficial tissues some of the organisms. JVb result. 



The entire series of inoculations was made in such a way that several 

 duplicate inoculations were made of all the germs present which could 

 possibly bear any relation to the trouble. The negative results point 

 to the possibility that there is some disturbance of the equilibrium of 

 the natural forces and physiological processes in the plant. This sus- 

 picion is strengthened by the fact that the cushion is not formed by 

 ordinary hypertrophy which is accompanied by increase of nutriment 

 at that point, and multiplication of cells. Ordinarily, thei'e is no 

 increase in the number of the cells. When this does occur it takes 

 place in the deeply seated cells which do not suffer collapse while the 

 more superficial ones bi-eak down. The increase in the number of cells 

 in such cases occurs simply by the formation of transverse walls in the 

 elongated cells. 



Is the trouble a 2)hysiological one f The abnormal stretching of 

 groups of cells to eight to ten times their normal size would then be 

 sought for in the excessive activity of one or more of the physiological 



