224 Maine Agricultural Experiment Station. 1920. 



Tests were made regarding the possibility of the existence 

 •of various means of transmission other than plant-lice. These 

 tests indicated that among the various conceivable means of 

 transmission plant-lice are distinguished from others by at least 

 a much greater effectiveness and probably by being the only 

 effective ones. The other means tested with negative results 

 were soil, flea beetles, Colorado potato beetles, the seed-cutting 

 knife, and contact of roots, stems, leaves, and seed-pieces. 



It appears that the most important measures to be taken 

 to prevent the spread of mosaic in a susceptible variety are 

 those which will reduce or prevent dispersal of plant-lice from 

 diseased to healthy plants. 



METEOROLOGICAL OBSERVATIONS. 



For many years the meteorological apparatus was located 

 in the Experiment Station building and the observations were 

 made by members of the Station Staff. June I, 191 1, the me- 

 teorological apparatus was removed to Wingate Hall and the 

 observations are in charge of Dr. James S. Stevens, professor 

 of physics in the University of Maine. 



In September, 1914, the meteorological apparatus was 

 moved to Aubert Hall, the present headquarters of the physics 

 department. 



The instruments used are at Lat. 44 54' 2" N. Lon. 64 

 .40' 5" W. Elevation 135 feet. 



The instruments used are the same as those used in pre- 

 ceding years, and include: Maximum and minimum thermom- 

 eters; rain gauge; self-recording anemometer; vane; and ba- 

 rometers. The observations at Orono now form an almost un- 

 Jbroken record of fiftv-two vears. 



