Nov. 8, 191 



Distribution of Virus of Mosaic Disease 



253 



Table I. — Occurrence of viriis in the placental structure and ovules of tobacco plants 

 affected with the mosaic disease — Continued 



Date of 

 inocula- 

 tion. 



Number of 

 plants. 



Material used for inoculation. 



Maryland Mammoth . 



Thin paste obtained by grind- 

 ing -with tap water in a mor- 

 tar thoroughly dry, loose, 

 ripened seeds from matured 

 capsules of plants affected 

 with mosaic disease. 



Same macerated material used 

 as in preceding test. 



Paste obtained by grinding to- 

 gether white immature ovules 

 from green capsules and dry., 

 loose, ripe seeds from healthy 

 plants. Small quantity of 

 tap water added to thin the 

 paste. 



Thin paste obtained by grind- 

 ing with tap water loose, dry, 

 thoroughly ripened seeds of 

 capsules from plants affected 

 with mosaic disease. 



Sap of green leaves from the 

 plants in the preceding test. 



Paste obtained Ijy grinding and 

 thinning with tap water dry, 

 loose, ripe seeds from cap- 

 sules of plant B affected with 

 mosaic disease. 



Thin paste obtained by grind- 

 ing with tap water the nearly 

 mature, lieht brown seeds 

 from ripening capsules of the 

 same plant B affected with 

 mosaic disease. In this test 

 the capsules selected were 

 still green and the placental 

 column succulent and full. 

 The seeds, which were firm 

 and brownish in color, still 

 adhered to the surface of the 

 placenta. 



Paste obtained by macerating 

 in a mortar with tap water 

 dry, loose seeds, nearly ma- 

 tured seeds, and leaves of 

 healthy plants. 



Paste obtained by macerating 

 with tap water the loose, dry 

 seeds from ripening capsules 

 of plants affected with mosaic 

 disease. These seeds were 

 mature, but the placental 

 column was still succulent, 

 although beginning to dry 

 and shrink somewhat. 



Macerated placentas from 

 which the seed in the preced- 

 ing test was removed. Small 

 quantity of tap water added 

 to obtain a thin paste. 



Paste obtained by macerating 

 with tap water in a mortar 

 the dry, loose seeds and pla- 

 centas of capsules obtained 

 from healthy plants. 



4 affected with mosaic 

 disease on June 10. 



2 affected with mosaic 



disease on June 10. 

 All healthy on June 10. 



7 affected with mosaic 

 disease on June 10. 



10 affected with mosaic 

 disease on June 10. 



I affected with mosaic 

 disease on June 10. 



affected with mosaic 

 disease on June 10. 



All healthy on June 10. 



affected with mosaic 

 disease on June 11. 



8 affected with mosaic 

 disease on June 11 



and 12. 



Earlier experiments' have shown that the roots, the apparently healthy 

 lower leaves, and the corollas of plants affected with the mosaic disease 

 sooner or later carry the virus of the disease. More recently experi- 

 ments have been carried out to determine whether the virus is present 



Allard, H. A. Mosaic disease of tobacco. U. S. Dept. Agr. Bui. 40, p. 18-1 



