156 CROWN-GALL OF PLANTS, 



{d') Alfalfa — no change except that milk is paler blue than on 

 August 13 and 19. 



{e') Salsify and grape have white pellicles and are much paler blue 

 than the others in this group (reduction probably taldng place slowly) ; 

 milk fluid, no separation of whey. No change in the others (all 

 deep blue) except that newest daisy has a pellicle (whitish). Milk 

 fluid in aU, and no separation of whey. Apple hairy-root is exactly 

 like check. Probably no growth. 



The Flats poplar was tested in milk with results ver^' difTerent 

 from those Brizi obtained with his Bacillus foimli: Three tubes of 

 sterile white milk were inoculated copiously on July 28, 1910, and 

 kept at 28° to 35° C. In 28 hours there was no visible change. In 

 4 days no separation of whey or change in appearance of the milk. 

 In 9 days a copious white bacterial pellicle, but still no separation of 

 the whey or curdling of the milk."^ 



SILICATE JELLY. 



The behavior of all tlie crown-gall organisms on silicate jelly was 

 much alike (one test only). There was a feeble to moderate white 

 growth divisible into two groups about as follows: 



(1) Smooth surface, growth rather scanty: Old daisy, newest 

 daisy, grape (? growth), new chestnut, arbutus, old ajDple, new apple, 

 apple hairy-root, beet, quince. 



(2) Surface papillate-rugose but smooth on the margins, growth 

 more abundant: Cotton, alfalfa, old rose. Turnip No. 1, hop, new 

 rose. Flats poplar. 



INOCUIAELE AND CROSS-IK-OCULABLE. 



Whether the different behavior of galls on various individuals of 

 different hosts, sometimes forming soft, rapidly developing spongy 

 excrescences and sometimes hard, slow-growing, slightly elevated 

 tumors, or abnormal clusters of roots, as for example in the apple, 

 is due principally to individual differences in rate of growth or 

 juiciness of the particular tissues involved, to the particular tissue 

 first infected, or to some other cause, must be left an unsettled 

 question. The writers are inclined to think that there are several 

 races of the gall-forming organisms varying more or less in amount 

 of virulence and in adaptability to various hosts. Starting from 

 soft gall of the peach, hard gall was produced on apple; and in the 



o On potato cylinders inoculated at the same time and from the same culture, the color of the slhie at 

 the end of 28 hours was wliite like that of the potato sulistralum. In 4 days the slime was thin and dirty 

 white. In days the bacterial layer, which had not increased much, was a dirty white, and the fluid 

 slightly brownish. The slime was not yellow and there was no marked action on the starch. .\t the end 

 of a month when tested with alcohol iodine the potato cylinder gave a strong starch reaction, but the color 

 was purple instead of deep blue (check;. 



213 



