ANNUAL REPORT, 1934 79 



from the standpoint of etiology and control. If the disease occurred as a filterable 

 virus or a bacterial infection alone, the problem of differential diagnosis and 

 control would be greatly simplified. But the investigations at this station and 

 others thus far indicate that infectious coryza is invariably complicated, — 

 filterable viruses of the common cold, infectious laryngotracheitis, and chicken 

 pox of low virulence, and avitaminosis being the primary factors, which lower 

 the resistance to bacterial infection of varying character to complicate the disease 

 picture and the method of treatment. Furthermore, the bacterial factors in 

 different outbreaks appear to vary in kind and virulence, and with respect to 

 locality, season, and breed. In some instances, as in the case of Hemophilus 

 coryza gallinarum and some forms of streptococci, they have been found to assume 

 a primary etiological role, independent of viruses and deficiency diseases. 



The greatest need at the present time is for practical diagnostic tests by which 

 the various forms of infectious coryza may be differentiated and specific treat- 

 ments applied. Attempts to discover such tests have been pursued throughout 

 the year in connection with the Diagnostic Service. The serological tests for 

 infectious laryngotracheitis reported above, the adaptation of the Nelson tech- 

 nique for the isolation and study of H. coryza gallinarum, and the use of Rosen- 

 heim's and Drummond's test for vitamin A deficiency in cases of infectious coryza 

 are some of the methods that have been used in the attempt to solve this problem. 



WALTHAM FIELD STATION 

 (Waltham, Massachusetts) 



Ray M. Koon in Charge 



For reports on approved projects conducted at this station, in addition to those 

 listed under this caption, see reports of the Departments of Botany, Entomology, 

 Floriculture and Olericulture. 



Along with its function as a research unit of the college, this station has con- 

 tinued to develop and advance in its usefulness as a center of information because 

 of its proximity to a dense population of varied horticultural interests. During 

 the past year there has been a marked increase in the number of telephone in- 

 quiries, requests fcr printed information, and visitors who have come to consult 

 the several members of the staff. 



The Boston Market Gardeners Association has continued to use the station 

 as headquarters for their monthly executive committee conferences and have 

 contributed much in the way of suggestions for worth-while projects. The Field 

 Station staff has, as usual, arranged the program of seven educational meetings 

 which the Market Gardeners Association holds during the winter months. 



The Sixteenth Annual Field Day was held on August 1 with a record attendance. 

 Over 1100 farmers and others engaged in activities relating to farming visited 

 the Field Station during the day, testifying to the interest in progressive horticul- 

 tural practices. Despite the exceptionally dry season, the demonstration and 

 experimental plots were in good condition for inspection. 



The Plant Houses. (P. W. Dempsey.) Continued interest in this project is 

 evidenced by the number of visitors who come to the Field Station especially to 

 examine the plant houses, and the steady demand for plans by mail. Both houses 

 were successfully operated during the past severe winter, proving them practical 

 for operation the year around if desired. 



