202 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



[Vol. 10 



even if the vascular system should be shown to constitute one 

 of the paths of this migration. Moreover, the power of migration 

 is not a matter which may be easily determined. 



The rapid and almost complete distribution of the organism 

 in the tissues accords well perhaps with a body minute in size 

 and attenuate in form, or else a body so fluid in character as to 

 be capable of assuming an extremely attenuate form. A living 

 structure so pliable and attenuate might be expected to be 

 sensitive to reagents and conditions. To a considerable degree 

 this sensitiveness is not true of the virus of mosaic. In our experi- 

 ments it resisted the usual procedure of dehydration by means of 

 acetone and alcohol. Modifications of the Buchner method for 

 the extraction of enzymes (zymase) from yeast cells were applied 

 to a pulp of fresh, diseased, leaf tissue ground with very fine 

 quartz sand, 5 parts of the former to 1 of the latter. Three 

 series of experiments were arranged. In the first, the pulp was 

 treated with full-strength acetone. There were 2 treatments, 

 each of 3 minutes, the tissue being drained after the first addition 

 of acetone and then fresh acetone applied for an equal interval. 

 Finally, the material was dried as promptly as possible under an 

 electric fan. In the second case the dehydration treatment con- 

 sisted in the addition of 95 per cent alcohol for a 3-minute interval, 

 followed by pure acetone, and finally dried, as above. In the 

 third case the treatment was 95 per cent alcohol, followed, in 

 the same intervals as before, with OS per cent alcohol, and 

 finally dried. After 3 days these residues were extracted with 

 water, each for 1 hour, using about 10 parts of water to 1 of the 

 dried material. .After the nitration of each extract through cotton, 

 20 plants were inoculated with each extract, and suitable (20) 



controls were maintained. These plants were under favorable 



growth conditions, and they exhibited the symptoms of disease 

 promptly. At the end of 19 days, 1 healthy plant only remained 

 in each set. All uninoculate< 1 controls remained healthy, and 

 the incidence of disease in the control which was inoculated with 

 diseased juice was likewise 19. 



When, however, the amount of alcohol and acetone was greatly 

 increased in relation to the bulk of material used (approximately 

 200 times as much), the incidence of infection was low, showing 



