154 REPORT OF OFFICE OF EXPERIMENT STATIONS. 



connection indicated no correlation whatever between winter egg pro- 

 duction and fertility of eggs during the hatching season, and also 

 showed that the higher the winter egg production the lower the per- 

 centage of fertile eggs hatched, and vice versa. 



In corn-breeding work the isolation of the genotype in sweet and 

 dent corn was followed by testing out different heterozygote types 

 and rejecting the undesirable forms. Careful measurements of 

 growth of the corn plant were made and accurate and full data on 

 the growth of corn under Maine climatic conditions were collected 

 for publication. 



The work of the entomological department during the year was 

 largely with plant lice, and especially with two closely allied species 

 of Macrosiphum, which are often very difficult to distinguish. The 

 only reliable basis of distinction of these two species, so far as known, 

 was detennined by this department during the year. Many of the 

 food plants of the species were also determined. The life history of 

 the alder plant louse was studied with a view to finding out whether 

 the life cycle is completed without going onto the maple. Four rare 

 aphid genera, Sipha glycerice^ Mindarus abietimis, Symdohius oh- 

 longus, and Mastopoda pteridisy were described during the year, and 

 work on the gall aphids of the elm was also published. The investi- 

 gations on the Chermes of Maine conifers were completed during the 

 past season. The systematic and morphological work on the fungus 

 gnats was also finished, and the extent of injury of certain species to 

 the potato in connection with the development of potata scab was 

 investigated. The maggots of diptera, including those of the house 

 fly and the birch leaf bucculatrix, were also under observation. 



The department of plant pathology continued work on the apple- 

 disease project, giving attention particularly to the interrelation of 

 several diseases and taking up new lines of work, specially on fruit 

 spots and leaf spots of the apple. A new species of Endomyces 

 which was isolated from decaying fruit of the apjDle in Maine was 

 described and the results of inoculating apples with the fungus, its 

 cultural characters, and a comparison of the species with other spe- 

 cies of Endomyces and with species of other closely related genera 

 were reported. 



In the continuation of the potato-scab work, scabby potatoes were 

 fed to different animals and the manure was applied to sterilized 

 soil to observe the possible transmission. On some of the horse 

 manure plats the potatoes were scabby, but on none of those where 

 cow manure was applied. The treatment of infected soils by grow- 

 ing diiferent kinds of crops was under test. Considerable progress 

 was made in the study of the blackleg disease of the potato, especially 

 with reference to the life history of the organism and the methods 



