June, 1913.] The Mosaic Disease of the Tomato. 
159 
and 26 from apparently normal fruit from diseased plants. All 
this second generation showed an intensive leaf reduction; the 
yellow spots appeared entirely inconspicuous. Variegated ex¬ 
amples did not occur. The plants grown in the garden showed 
abnormal appearances all at the same age. Leaf reduction 
was less noticeable, although leaf apexes and side shoots were 
somewhat abnormally developed. A pronounced case of disease 
did not occur. In the greenhouse, the plants showed indefinite 
cases of mosaic disease. One plant out of 27 had strong symptoms 
of leaf reduction. She states (p. 17), ‘‘By the field experiments 
it has been shown without a doubt that the disease is inheritable. 
Also here it is shown that the light factor is important in develop¬ 
ing the disease. ” 
Resistance and Selection .—Hunger (1905) believes through 
proper selection a resistant strain of tobacco can be obtained, 
(p. 297). “On page 282 it was shown how diversely plants 
may develop from Deli seed, even when of the same variety, 
and I am convinced that it is possible, through proper selection 
of such seed to isolate and obtain constant physiological strains 
whose peculiarities would remain fixed within certain limits of 
temperature.” Bouygeres and Perreau (1904) claim to have 
reduced mosaic disease 98% in a season by selecting seed from 
a plant which remained healthy among a diseased lot. 
Various Names for Same Disease. 
Considerable confusion and dispute exists among European 
investigators, as to whether Pockenkrankheit, Fleckenkrankheit 
(Spot disease) and mosaic disease, are the same or different. 
Mayer (1886) describes the Mosaikkrankheit, in its second stage 
by saying that the yellow areas gradually become brown and 
eventually dry up. These are also the views held by Prillieux 
and Delacroix (1894); and Marchal, Gontiere and Bouygues 
(according to Hunger 1905). This stage corresponds to the 
disease described as Pockenkrankheit by Iwanowski (1892) (b), 
who noticed it in 1888, and on account of the differences in ap¬ 
pearance gave it the distinctive name, ‘‘Pockenkrankheit, ” 
(Pox Spot). He says (p. 68), “The Mosaic disease is contagious, 
but such is not the case with Pockenkrankheit. The condition 
producing Pockenkrankheit is excessive transpiration. ” He 
criticises (1902) Beyerinck, Koning and Heintzel for considering 
Pockenkrankheit and mosaic disease the same trouble. On the 
other hand, Delacroix (1905) assigns the name “rouille blanche,” 
to a spotting of tobacco caused by a specific bacterium. He says 
“rouille blanche” must be limited to the so-called Pockenkrank¬ 
heit, as named by Iwanowski. Westerdijk (1910) states that 
Pockenkrankheit (“necrobiotische form”), does not occur on 
the tomato, but that it is very common on tobacco; even more 
