EXPERIMENTS WITH THE BEET ORGANISM. 83 



The 68 plates poured from the 20 c. c. fluid (contents of the tumor 

 plus possible contaminations from the air) gave the following results: 



(1) After 24 hours at 23° C: Sixty-four plates sterile; 4 plates 

 contain a total of 10 colonies. 



(2) After 48 hours at 23° C: Fifty-seven plates sterile; 11 plates 

 contain a total of 17 colonies — 2 of them a widespreading white 

 organism. All the other colonies are tiny, white, and buried. 



(3) After 72 hours at 23° C. : There are now 298 additional colonies 

 all small, slow-growing, white, and buried. Twenty-seven plates are 

 still sterile so far as the hand lens indicates, and a number of these 

 received 0.5 c. c. volumes of the fluid. Plate 67 was rejected from 

 the count because overrun and spoiled by a white colony. 



(4) After five days at 23° C. : There are now 792 additional colonies 

 not counting those on two plates (53 and 59) which are now overrun 

 and spoiled by a white rapidly growing organism. All of these 

 colonies are small, white, slow-growing, and most of them buried. 

 Twenty-two plates are still free from colonies. These received the 

 smaller inoculations, but much more fluid than one ordinarily expects 

 to use, viz, most of them 2 to 10 drops. 



(5) After seven days at 23° C: (a) Thirty-seven plates show no 

 additional colonies; (h) 2 more plates (50 and 57) rejected because 

 contaminated; . (c) on the rem.aining 29 plates there are 386 additional 

 colonics, all small and mostly scattered, rarely small clusters on a 

 tiny fragment of tissue. 



Two plates of lot c contain each 1 Penicillium spore and 2 yellow 

 ntruding colonies. The colonies which came up at the end of 24 

 and 48 hours may be regarded as contaminations from the air. Those 

 on the 5 rejected plates may also be neglected. Of the remainder 

 very few can be regarded as air borne. 



(6) On the ninth day nearly all the white colonies are still buried 

 and small and it is too early to say what proportion of these are the 

 parasite. A few of the most hopeful-looking ones were transferred 

 to bouillon. 



(7) On the fifteenth day those previously transferred to bouillon 

 as hopeful were rejected and 13 other colonies were marked for 

 transfer, most of these having appeared after the ninth day — in other 

 words, of the 1,500 colonies which developed onl}^ 1 per cent had the 

 appearance on the plates of the right organism. Of these colonies 

 only 2 proved pathogenic, i. e., produced tumors when inoculated 

 into sugar beets, and these yielded very small slow-growing galls as if 

 feebly virulent (PI. XXXVI, fig. 1). It should be stated, however, 

 that the beets were not growing much. 



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