16 MASS. EXPERIMENT STATION BULLETIN 398 



Bacteriological Studies of Rural Water Supplies. (James E. Fuller.) This 

 project has been started within the year. Some preliminary work along this 

 line has already been reported (James E. Fuller and Sonnia Levine, Mass. Agr. 

 Exp. Sta. Bui. 378, 1941). Present experiments are being done on an amplified 

 scale. The study aims to attempt a differentiation of the intermediate members 

 of the coliform group of bacteria, so frequently encountered in rural water sup- 

 plies (wells or springs), to learn how many of them indicate serious pollution and 

 how many indicate merely surface wash. The differential reactions (Imvic tests) 

 of these bacteria are being studied at several incubation temperatures, from room 

 temperature to 46°C. (Eijkmann-test temperature), to determine the proportion 

 that are related to the fecal Escherichia coli. Present indications are that the 

 use of the Eijkmann-test temperature for incubating the Imvic tests may be 

 useful in evaluating the sanitary quality of rural water supplies. 



Laboratory Service. (R. L. France, until Julv 1942 ; James E. Fuller, beginning 

 July). 



Milk (bacteria counts) 392 



Ice cream (bacteria counts) 91 



Milk (butter fat) 27 



Water 107 



Miscellaneous 3 



DEPARTMENT OF BOTANY 

 A. Vincent Osmun in Charge 



Diseases of Trees in Massachusetts. (M. A. McKenzie and A. Vincent Osmun.) 



The Dutch Elm Disease Problem. The Dutch elm disease caused by the fungus, 

 Ceratostomella itlmi (Schwarz) Buisman, and spread by bark beetles was found 

 in Massachusetts in 1941. During 1942, investigation of this disease in the State 

 has had three main objectives: the discovery and eradication of diseased trees; 

 the evaluation of the importance of woodpiles as sources of the causal fungus and 

 carrier beetles; and the elimination of conditions favorable to the spread of the 

 disease. 



Results of the inoculation of several species of elm with the causal fungus in 

 early summer under controlled conditions in the greenhouse indicate that all 

 species of elm are susceptible; but American elm ( Ulmus americana L.) showed 

 symptoms of the disease most promptly and succumbed most rapidh- of all 

 species, potted plants of the species being completely killed within 10 days after 

 inoculation. Death presumably is due to a toxin produced b}- the fungus, but the 

 word "toxin" is here employed only in a nonspecific sense. Studies previously 

 reported bj' others, as well as the writers' investigations, indicate that micro- 

 scopic symptoms indistinguishable from those resulting from fungus infection 

 may occur in plants variously treated with sterilized extracts from fungus cultures. 

 If the symptoms are associated with a specific toxin, a neutralizing agent may be 

 found, although no consistently reliable agent has been found by the writers. 



Considerable interest in the work has been shown by municipal tree depart- 

 ments and private citizens, and many specimens for laboratory study were re- 

 ceived during the past year. Through the cooperation of the United States 

 Bureau of Entomology and Plant Quarantine, valuable information relative to 

 the general distribution of the disease has been obtained regularly. Seven dis- 

 eased trees have been eradicated in Massachusetts: in 1941, 1 in Alford; in 1942, 

 3 in Egremont, 1 in Great Barrington, 1 in Westfield, and 1 in Sheffield. The 



