47° BOTANICAL GAZETTE [JUNE 
rather than truck gardeners, so that the fields are widely scattered 
through the country, and as a rule are not in the neighborhood of 
hothouses. Hothouses, therefore, can play only a very minor réle 
as reservoirs of mosaic infection for the canning tomato crop. 
Transmission with tomato seed 
Miss WESTERDIJK (12), in her work with tomato mosaic, con- 
cluded that the disease was transmitted through the seed, but her 
evidence appears to be based on a field test with only ninety-six 
plants, and these unprotected from insects. ALLARD (3), in exten- 
sive tests involving about a thousand plants grown from seed from 
mosaic tomato plants, obtained no evidence whatever that the 
disease was transmitted through the seed. The same investigator 
(2) found that the related tobacco mosaic is not seed-borne. 
The general occurrence of mosaic in fields used as a source of 
seed for the canning tomato crop of Indiana made it necessary to 
test thoroughly the possibility of seed carriage of the virus. A 
quantity of tomato seed was saved from mosaic tomato plants in 
the fall of 1920, in cooperation with I. C. Horrman and H. D. 
Brown of the department of horticulture, and was planted in a 
greenhouse December 2, 1920. Because of the season the plants 
grew rather slowly. Ina careful examination made on January 20, 
1921, no mosaic was found in a total of 13,573 of these plants. The 
crop was thinned at this date, and on February 26 no mosaic was 
found among the 2823 plants which remained. On February 3, 1921 
seed saved from two mosaic tomato plants in 1920 was planted in 
soil flats in the greenhouse, and in the 135 plants present on May 9 
no mosaic had appeared. In the summer of 1921 another test of 
tomato seed collected from mosaic plants in 1920 was made in the 
greenhouse and under a cloth cage in the field. The seed was 
planted on June 23, and on August ro no mosaic was found in a 
total of sog1 plants in the greenhouse and 218 under the field 
cage. Thus, ina total of 19,017 plants grown from seed from mosaic 
tomato plants, no mosaic appeared. Similar tests in the greenhouse 
in 1921 with two-year-old tomato seed from mosaic plants also 
yielded negative results. In a total of 3927 plants grown from such 
seed no mosaic occurred. | 
