Ri-siiARCH ON Plant Tumors 509 



up a most intcrestii^t; field for further research." In his paper 

 Smith acknowledged that had he read, when it appeared in 1913, 

 Loeb's " latest remarkable book," Artijuicil l\trthc)inge>icsis atid 

 FertiUz.ition, his work would have been advanced by " at least 

 two years." Loeb"s '" many positive and splendid results with acids 

 on animal eggs " were correlated with his work more explicitly 

 in his paper, " Mechanism of overgrowth in plants." ^^ His first 

 illustrative slide showed "chemical findings" and on this slide, 

 he pointed out, 



I have starred the substances with whiih I have now produced over- 

 growths in plants and'have italicized those which Dr. Jacques Locb had 

 previously found in his experiments on animal eggs to be most effective 

 in causint; unfertilized eggs to begin to grow. That there should be so 

 many of these egg-starting substances excreted by a tumor-producing para- 

 site is not only*^ astonishing but extremely suggestive. All of them are 

 substances which pass readily through protoplasmic membranes. 



TABLE I. Showing Products of Bacterium tumejaciefjs. 



* Ammonia Alcohol *Formic Acid 



* Amines Acetone Carbonic Acid {}) [supplied by Smith for 

 *Aldehyd ''Acetic Acid reasons given] 



Smith directed attention " especially to the substances the names 

 of which [he had] starred as compounds with which to experi- 

 ment singly and combined, and in a great variety of dilutions. 

 With each one of these substances, in the absence of bacteria," 

 he said, " I have obtained on suitable plants decided overgrowths, 

 growths which I think I am warranted in designating as incipient 

 crown galls." He showed slides presenting results obtained with 

 ammonia, dimethylamine, formaldehyde, acetic acid, and formic 

 acid. He reminded his audience of Von Schrenk's intumescences 

 on cauliflower from copper salts, and he explained in some detail 

 Dr. Bernhard Fischer's overgrowths of epithelium in rabbit's ears 

 (1906) caused by injections of scarlet red and indophenol. Other 

 substances than these wdiich can cause overgrowths were now 

 known, substances some of which were known to be products 

 of tumor-producing parasites. The new investigations were a 



challenge. 



On April 19 Smith participated in ceremonies which dedicated 



" 0/'. cit., 439-440. 



