104 EEPOET OF OFFICE OF EXPERIMENT STATIONS. 



last year in the Proceedings of the American Veterinary Medical 

 Association. Under California conditions the use of bovovaccine 

 seemed to produce some immunity, but to fail in protecting calves 

 until 2| years old. It was also found that tuberculosis sometimes 

 spreads rapidly in cattle under strictly outdoor conditions. The 

 retesting of cattle within six weeks, even when Vallee's method was 

 used, Avas unsatisfactory, as it was observed that some tubercular 

 cattle will not react to tuberculin on retesting even after three 

 months. Guinea-pig inoculations with the blood sediments of 20 

 tuberculous cattle failed to produce tuberculosis. Tubercle bacilli 

 experimentally thrown into the blood streams were rapidly removed 

 from the circulation, which is regarded as indicating that the capil- 

 laries of the lungs are more efficient in arresting bacilli than the 

 peripheral capillaries. 



The cause of sterility of almond trees was further investigated, 

 numerous microscopical studies of the pollen of many varieties being 

 made in the laboratory and in the field. It was brought out by these 

 studies that the pollen of the better varieties of almonds, known as 

 the Hatch varieties, is almost uniformly physically imperfect, while 

 pollen of such varieties as Drake Seedling and Texas Prolific, as well 

 as that of certain nameless seedlings, was found regular in form, 

 plump and well rounded. These facts are believed to explain the 

 noted self-sterility of the Hatch varieties and the reputed value of 

 Drake Seedling and Texas Prolific as cross-poUenizers. These con- 

 clusions were largely confirmed by the results of field experiments. 

 The experimental plantings of almonds have been increased to 16 

 named varieties, planted in groups of five. These plantings, as well 

 as the laboratory, are located at Davis. 



A number of different lines of work were prosecuted with funds 

 provided through the Hatch Act and State appropriations. Breed- 

 ing work with individual wheat plants for nitrogen and also for 

 yield were conducted, together with experiments on green manuring 

 with field peas in wheat culture. One object in view is to overcome 

 the apparent necessity of practicing bare fallow. At present the 

 station fields average 36 bushels, the land being fallowed every other 

 year. Variety and culture tests with various crops were also in 

 progress at Davis, and some work on cotton was pursued in the 

 Imperial Valley. 



The entomological department cooperated in the study on the phyl- 

 loxera and also gave attention to the control of the peach-tree borer, 

 thrips, and mosquitoes. One of the county entomologists, cooperat- 

 ing with the department, found that banding the trunks with 

 asphaltum is very effective in controlling the peach-tree borer. 

 Spraying heavily with lime gave good results in combating thrips. 



