6i8 



Journal of Agricultural Research 



Vol. X, No. 12 



Table III. — Effect of oiie inoculation as compared with several inoculations in young 

 plants. Inoculations made with a needle, introducing the virus into each puncture 



Number of plants 

 inoculated. 



Number 

 of inocu- 

 lations. 



Distribution of inoculations. 



Date in- 

 oculated. 



Per- 

 centage 

 mosaic. 



77 Maryland Mammoth. 

 76 Mar^'land Mammoth. 

 54 Maryland Mammoth. 

 44 Maryland Mammoth. 



103 Maryland Mammoth 

 109 Maryland Mammoth 



41 (first-generation hy- 

 brid). 

 54 Maryland Mammoth. 



so Connecticut Broad leaf 

 Do 



10 Connecticut Broadleaf 



Do 



Do 



Do 



Do 



Do 



Do 



Do 



Do 



Do 



Do 



Do 



Do 



Do 



Do 



Do 



Do 



Do 



Do 



Do 



Do 



Do , 



Do 



Do 



Do 



Do 



Do 



Do 



Many. 



I 

 Many. 



Many. 

 Many. 



One in one leaf 



One in each of two leaves . 



One in one leaf 



One in each of two leaves . 



One in one leaf 



Two in one leaf; one in a second 



leaf. 

 One in one leaf 



In all the leaves. 



In middle of one leaf near midrib. . 

 In all the leaves 



One in middle of one leaf near mid- 

 rib. 



Two in one leaf, one on each side 

 midrib near middle. 



Two in one leaf, one in second at 

 middle near midrib. 



Two in each of two leaves near 

 middle, and one on each side mid- 

 rib. 



In all the leaves. 



With tap water in all the leaves 

 (control). 



One in one leaf , 



One in each of two leaves 



One in each of three leaves , 



One in each of four leaves 



One in each of three leaves; two in 



a fourth. 



Two in each of three leaves 



Two in each of three leaves; one in 



a fourth. 



Two in each of four leaves , 



Two in each of four leaves; one in 



a fifth. 



Many. 



One in one leaf 



One in each of two leaves 



Two in one leaf; one in a second leaf. 



Two in each of two leaves 



Three in two leaf; two in a second 



leaf. 



Two in each of three leaves 



Four in each of two leaves 



Five in one leaf; three in a second 



leaf and two in a third leaf. 



In all the leaves 



....do 



...do 



With tap water in all the leaves. . . 

 ...do 



1915- 

 Jan. 13 

 ..do... 

 ..do... 

 ..do... 



Jan. 9 

 ..do... 



.do... 

 .do... 



May 8 

 ..do..., 



Aug. 24 

 ...do.... 

 ...do.... 

 ...do.... 



.do... 

 .do... 



Dec. 

 ..do. 

 ..do. 

 ..do. 

 ..do. 



..do. 

 ..do. 



,.do. 

 .do. 



1916. 

 Jan. 3 

 ..do.. 

 ..do.. 

 ..do.. 

 ..do.. 



..do. 

 ..do. 

 ..do. 



..do. 

 ..do. 

 ..do. 

 ..do. 

 ..do. 



5 mosaic . . . 

 22 mosaic. . 



6 mosaic . . . 

 25 mosaic . . 



13 mosaic . . 

 71 mosaic . . 



3 mosaic . . . 



45 mosaic . . 



7 mosaic . . . 

 so mosaic . . 



AU healthy, 



do 



1 mosaic . . . 



....do 



7 mosaic . . . 

 All healthy, 



3 mosaic . 

 S mosaic . 

 3 mosaic . 

 8 mosaic . 

 ....do... 



9 mosaic . . . 



8 mosaic . . . 



6 mosaic . . . 



9 mosaic. . . 



All healthy, 



3 mosaic . . . 



4 mosaic. . . 



5 mosaic. .. 



6 mosaic. .. 



5 mosaic. . . 

 ....do 



10 mosaic . . 



9 mosaic . . . 



10 mosaic . . 

 8 mosaic . . . 

 All healthy. 

 ....do 



6 

 28 

 II 

 56 



12 

 65 



7 



83 



14 

 100 



50 

 100 



100 

 80 



THE QUESTION OF RESISTANCE TO MOSAIC DISEASE IN TOBACCO 



PLANTS 



In a series of plants, even though a large number of inoculations may 

 be made in the leaves of each plant as nearly as possible in the same 

 manner, a few plants may escape infection and remain free from the 

 disease until maturity. 



Experiments have been carried out to determine whether such plants 

 produce progenies which are more or less resistant to the disease. In 

 one series 50 young Connecticut Broadleaf plants were inoculated at one 



