WILT DISEASES OF TOBACCO. 265 



A part of the rods in young agar streak cultures made from Honing's organism (third 

 sending, which is actively pathogenic) were actively motile (darting about when examined 

 in water), and the appearance of some of these rods when stained is shown in fig. 1340, 

 which may be compared with figs. 109 and 133. I can not, therefore, explain Hutchinson's 

 statement that Bad. solanaccarum is non-motile unless it be that he did not wait long 

 enough. Frequently when young solid cultures are transferred to distilled water they are 

 not at once motile, but become actively motile in an hour or so. 



After the above results were obtained one additional test was made with the Sumatran 

 organism. Eight typical looking colonies were subcultured from an agar poured plate. 

 Each one of these 8 cultures was then examined in hanging drop and a portion of the rods 

 in each observed to be actively motile (darting movements). Each one was then used to 

 inoculate (by needle pricks) one young tobacco plant and within 7 days each one of these 

 8 plants developed typical signs of the tobacco wilt ; the bacterial lesions were demonstrated 

 in the stems, and the Medan organism was plated out again from two of the plants. Sub- 

 sequently polar flagella were demonstrated on a small portion of the rods in two of these 

 cultures, but the cultures proved very refractory to stains (Van Ermengem's, Pitfield's, 

 Lowit's, Morton's night blue, etc.), and no fine slides were obtained. The greatest number 

 of motile rods were observed in the top layers of 10 or 15 c. c. of autoclaved distilled water 

 added to young agar streaks and allowed to stand for some hours. Treated in this way fully 

 one-half the rods were visibly motile. 



In our nutrient gelatin liquefaction did not occur, at least not during the first seven 

 weeks. 



Tests of Medan III in 3 fermentation tubes using water, Witte's peptone and cane 

 sugar, gave the following results at the end of a month : well clouded in the open end and 

 the U copious precipitate, no pellicle, fluid in the bowl browned, reaction to neutral litmus 

 slightly alkalin. In the closed end: no clouding, no gas. 



Using first lactose and then glycerin in place of cane sugar, similar results were 

 obtained, except that with these carbon foods there was less growth, as indicated by the 

 scanty precipitate, and no browning of the fluid, which was alkaline at the close of the 

 experiment in all of the tubes. 



At the end of a month in two fermentation tubes containing nitrate bouillon there was 

 a scanty stringy growth in the fluid of the open end, which was now clear. There was no 

 gas, no stain, no clouding of closed end, and the fluid was alkaline. 



Old litmus-milk cultures of Medan III yielded no crystals [see p. 233]. 



THE RUSSIAN DISEASE. 



Iwanowski has described a rot of tobacco from Bessarabia, which I have included here 

 somewhat doubtfully. He does not say in so many words that it is due to bacteria or that 

 he has seen bacteria in the tissues, but he does say that none of the higher fungi were present. 

 The signs are decayed spots which enlarge and fuse. These occur on various organs. The 

 bark is first attacked and then the wood and pith, or the reverse. The Russian paragraph 

 dealing with this disease reads about as follows : 



Rot is the name the author gives to a disease of tobacco, which consists of peculiar decayed spots 

 appearing on the stem, leaves, flowers, seed-capsules in a word, on all parts of the plant. It is as 

 likely to occur on one part of the plant as another. The spots may group themselves around the 

 stem, girdling the stem, or frequently they group themselves on one side of the stem, on which side 

 the stem bends over. It often occurs that the decayed spots unite with one another in a transverse 

 direction. The rot attacks either the bark alone, or also the cambium, the wood, and the pith, or it 

 may act in the reverse order. In a given spot the wood may be decayed, but the bark be entirely 

 healthy. The root in such a case commonly becomes decayed. The distribution of this disease on 

 the plantation is similar to that of the spot-disease, that is, the diseased plant does not become the 

 center of infection. Unlike the spot-disease, there is almost no reference to this disease in literature. 

 Concerning its cause, it is only clear to the author that it is not of fungous origin ; whether it is caused 

 by bacteria it is not yet possible to say, but nothing stands in the way of this supposition. 



