August 13, 1909] 



SCIENCE 



223 



type, while slender-limbed strains witli a fine 

 narrow face, a well set-on tail and a mane that 

 clings to the neck, probably most accurately 

 reproduce the variety of E. gracilis which in 

 prehistoric times inhabited north Africa. 



J. C. EWART 



University of Edikbukgh 



THE SOCIETY OF AMERICAN 

 BACTERIOLOGISTS ' 

 The Etiology of Plant Tumors: Ebwin F. Smith. 

 (Illustrated by numerous stereoptlcon photo- 

 graphs. ) 



The author prefaced his remarks with the state- 

 ment that Dr. C. O. Townsend and Miss Nellie 

 Brown were associated with him in the prosecu- 

 tion of this research. The address consisted of a 

 series of lantern slides with running comment. 

 The slides showed inoculated plants of various 

 species and of widely diflferent families, the 

 growths in all cases being the result of pure cul- 

 ture inoculations of the schizomycete Bacterium 

 tumefaciens. The crown gall of cultivated plants 

 is cross inooulable to an astonishing degree. In 

 susceptible tissues the signs of these galls appear 

 within as short a time as four or five days. The 

 tumor continues to grow for several months and 

 in some cases for several years and may become 

 5 cm. or more in diameter. Hundreds of pure 

 culture inoculations have been made. The organ- 

 ism cultivated from the Paris daisy has been in- 

 oculated many times successfully into the same 

 and also into the peach, rose, hop, sugar-beet, white 

 poplar and other susceptible plants. That from 

 the crown gall of the peach has been many times 

 successfully inoculated into the peach, and also 

 into the Paris daisy, sugar-beet, hop and other 

 plants. The schizomycete from the hop has been 

 inoculated successfully into the hop and into 

 the Paris daisy, sugar-beet and other plants. 

 One of the astonishing things about this crown- 

 gall organism is the nimiber of families which are 

 subject to infection; in other words, the very 

 simple and generalized nutritional needs of the 

 parasite. In some ways it resembles the root- 

 tubercle organism of Leguminosae, but is not iden- 

 tical. It has been inoculated into clovers with the 



'In session December 29-31, 1908. These ab- 

 stracts were received after the general report of 

 the society had been printed in the issue of Sci- 

 ence for June 25. 



production of knots. Quite recently from the 

 hard gall of the apple (selected by Dr. Hedgcock) 

 we have isolated an organism which appears to be 

 like that occurring in other crown galls, and with 

 this, hard galls have been produced upon the Paris 

 daisy. A similar if not identical organism has 

 also been isolated from the hairy root of the 

 apple and successfully inoculated into the sugar- 

 beet, i. e., with the production of similar root- 

 tufts at the point of inoculation. There is now 

 little doubt, therefore, that the hairy root of the 

 apple is also of bacterial origin. 



Metastatic gro'n-ths occur on these plants, but 

 up to this time we have not definitely determined 

 the channels of infection from the primary tumor 

 to the secondary ones. These are easily discovered 

 in the case of the olive-tubercle, but are not 

 readily found in case of these crown galls. The 

 same remark is true respecting the bacteria in the 

 primary tumors. They are very abundant and 

 easily discovered in the olive-tubercle, but not 

 readily detected in the crown gall, although ob- 

 tainable therefrom in Petri dish cultures on agar. 

 It is still too early in the course of our studies 

 to make positive statements respecting the like- 

 ness or unlikeness of these growths to malignant 

 animal tumors, but it is proposed to continue 

 this phase of the inquiry. There is in these 

 growths a very rapid multiplication of paren- 

 chymatic tissues with reduction and distortion of 

 the firm conductive tissues of the plant and the 

 final decay and sloughing off of the spongy tissues, 

 leaving open wounds, on the margins of which 

 fresh developments of the tumor may appear. 



Seed Corn as a Means of Disseminating Bacteriwm 



Stewarti: Ebwin F. Smith. 



In the summer of 1908, in a hothouse on the 

 grounds of the Department of Agriculture, the 

 writer succeeded in obtaining from plants grown 

 from a suspicious seed corn eight times as many 

 cases of Stewart's disease as from plants grown 

 from disinfected seed taken from the same sack. 

 The plants were treated in all respects exactly 

 alike, except that a portion of the seed corn was 

 planted without disinfection and other portions 

 were subjected for ten minutes and fifteen minutes 

 to 1:1,000 mercuric chloride water. The mere 

 statement that there were eight times as many 

 cases in the plants grown from untreated seed by 

 no means expresses the whole truth, because in 

 the plants grown from treated seed all the cases, 

 with four exceptions, were very slight ones, every 

 plant being reckoned as diseased which showed a 



