18 MASS. EXPERIMENT STATION BULLETIN 417 



substantially increased over those obtained by the "Standard Methods" proced- 

 ure. Several commercial wetting agents were employed, as well as Ivory soap. 

 None gave sufificiently improved results to justify their use in routine plating. 



Vitamin and Amino-acid Requirements of Non-pyogenic Streptococci. (James 

 E. Fuller and Ruthe Galler.) Certain of the non-pyogenic streptococci from the 

 mouth or intestines are considered of importance as indicators of pollution. All 

 of these types may be found in swimming pool water, and those from the mouth 

 have been suggested as logical indicators of unsatisfactory cleaning of eating 

 and drinking utensils. There are no simple direct methods of identifying these 

 organisms and this study was made in the effort to develop some such method. 



Representative non-pyogenic streptococci were cultivated in a synthetic 

 medium. Vitamins (riboflavin , pantothenic acid, and pyridoxine) and amino acids 

 (tryptophane, tyrosine, lysine, argenine, methionine, valine, and glutamic acid) 

 were incorporated in the medium in various combinations. Each organism re- 

 quired all of the amino acids and all of the vitamins employed. It was not pos- 

 sible to substitute para-aminobenzoic acid for any of the vitamins mentioned. 



Laboratory Service, December 1, 1942, to June 30, 1944. (James E. Fuller.) 



Milk, bacteria counts 297 



Ice cream, bacteria counts 115 



Water, bacteriological tests 191 



Total 603 



DEPARTMENT OF BOTANY 

 A. Vincent Osmun in Charge 



Diseases of Trees in Massachusetts. (M. A. McKenzie and A. Vincent Os- 



man.) 



The Dutch Elm Disease Problem. Ceraiostomella iilmi (Schwarz) Buisman, 



the causal fungus of the Dutch elm disease, has been isolated from 17 trees in 



eight municipalities in Massachusetts, and to date (June 1944) affected trees 



have been removed and burned as follows: 



1941 1942 1943 1944 



Alford 1 



Egremont 3 2 2 



Great Barrington 1 1 1 



Mount Washington 1 



Pittsfield 1 



Shefifield 1 1 



Westfield 1 



West Stockbridge , 1 



Breakage of trees caused by ice storms in December 1942 and Januar}- 1943 

 contributed to the increase in elm material suitable as breeding places for the 

 principal carrier of the disease, a bark beetle {Scolytus multistriatus Marsh.). 

 The beetle is now known to be present generally in Massachusetts east of Wor- 

 cester County and has been reported widely in Berkshire County and Hampden 

 County in addition to six towns in Hampshire County. 



In an attempt to reduce the quantity of elm items which might contribute to 

 the spread of this disease, municipal tree departments cooperated in a program 



