CHEMISTRY OF ORGANISM. 175 



Another portion of the culture was acidified and shaken out \vith ether. The ether 

 was driven off, leaving a yellow, oily residue which contained a very small quantity 

 of colorless, radiating, short prisms. These were insoluble in water, and had every 

 appearance of fat. It was attempted to discover whether the residue contained any 

 other acids, by preparing the barium salts and fractionating them by means of abstrac- 

 tion with absolute alcohol. No lactic or succinic acid could be detected. The resi- 

 due fi'om the ether seemed to consist mainly of a little fat and some fatty acids. 



The calcium carbonate, which remained in the flasks, was removed from the cul- 

 tures by filtration in hydrochloric acid and extracted with ether, and no acids passed 

 into the ether extract, so that this precipitate does not seem to have contained any- 

 thing besides the calcium carbonate. 



Summary: A considerable quantity of acetic acid and ethyl alcohol was identified 

 in the culture medium. No other fermentation acid could be detected. There 

 seemed to be present a small amount of fat or fatty acids. 



THE STIMULUS TO GROWTH. 



All plant tumors arc not due to the same parasite, but all the 

 hyperplasias are due probably to the same chemical substance or to 

 closely related substances, whatever the organism may 1)3 that 

 produces these growths. This substance, which we shall eventually 

 isolate, is probably a by-product of the growth of the intruding 

 organism, ]3ossibly a complex colloitl, or perhaps only some compara- 

 tively simple substance acting continuously in minute quantities. It 

 is our hope finally to cause the crown-gall with s})ecific products of 

 the bacterial growth freed from the living organisms and from extra- 

 neous substances, and we have under way already certain experi- 

 ments of this sort, but they are not yet ready to be reported on. 



As a first worldng hypothesis we have assumed some salt of acetic 

 acid, possibh" ammonium acetate, to be the cause of the stimulus, 

 either, (1 ) as the primary source of the irritation, or, (2) as the 

 liberator of such an irritant from the protoplasm of the bacteria 

 through its killing action on their membranes, which would render 

 them permeable. 



PHYSICAL CHANGES— EARLY DECAY. 



The physical changes in the tumors are such as would naturally 

 occur in any rapidly proliferating parenchyma imperfectly provided 

 with conductive tissues. It would seem that beyond a certain point 

 the soft tissues can not be sup{)lied wdth water and food, and decay 

 sets in with more or less slougliing of the tumor and the appearance of 

 open wounds. The harder and more slow growing the gall the later 

 this appears. A variety of saprophytic bacteria and fungi take part 

 in disintegrating the overgrown tissues. Among these saproj)hytic 

 bacteria there are several white forms closely resembling the gall 

 organism as grown on agar poured plates, dendritic white forms, green 

 fluorescent species, yellow species, orange species, pink species, etc. 



213 



