620 



Journal of Agricultural Research 



Vol. X, No. 12 



extreme forms of malformation of the leaves and catacorolla frequently 

 come into expression. The blossoms and leaves of healthy plants given 

 the same treatment remain normal indefinitely. 



SUBSEQUENT DISTRIBUTION OF THE VIRUS OF MOSAIC IN INOCU- 

 LATED LEAVES AFTER CUTTING THE MIDRIBS OR LATERAL 



VEINS 



In February, 191 4, a series of tests was made to determine the effect 

 of severing the midrib or the lateral veins upon the subsequent distribu- 

 tion of the virus in an inoculated leaf. In one series the midrib alone 

 was carefully severed close to the base of the leaf blade (Pi. 63, leaf A). 



In a second series the lateral veins were cut in the same manner 

 along either side of the midrib (PI. 63, leaf B). 



In a third series a cut was made close to the midrib from a point near 

 the apex nearly to the base on one side of the leaf, thus severing all the 

 larger lateral veins on this side (PI. 63, leaf C). 



A sharp scalpel heated to redness was used for all cutting. This 

 method not only insures complete sterilization of the instrument, but 

 also serves to kill the tissues immediately in contact with the blade, thus 

 searing over the freshly cut surfaces. After a brief wilting, turgidity is 

 again established and growth and assimilation maintained, although more 

 slowly, as would be expected (Table IV). 



Table IV. — Effect of severing the midrib or lateral veins, follouing inoculation, upon 

 the distribution of the virus in the plant 



o About. 



