ANNUAL REPORT, 1939 21 



Streptococci in Swimming-Pool Water. (Ralph L. France.) Results obtained 

 in this study indicate that the "streptococci" isolated from the water in the 

 college pool came from the body surfaces of the swimmers, and are not of in- 

 testinal origin. Further, the evidence indicates that while the bacteria appear 

 as "streptococci" in the prelininary isolation media, biochemical and morphologi- 

 cal tests identify the majority as micrococci. Their public health significance 

 remains at present an unknown quantity. 



Further biochemical tests will be made on these organisms, particularly their 

 salt tolerance, chlorine tolerance, and ability to grow in a medium with a high 

 alkaline reaction. 



Co-operative Study of Milk Plating Methods with the Food and Drug Division 

 of the State Board of Health. (Ralph L. France.) A comparative study of media 

 and methods for plating market milk is being made with the Food and Drug 

 Division. 



Laboratory Service. (Ralph L. France.) Following is a list of the types and 

 numbers of examinations made during the past year. 



Milk (bacteria counts) 893 



Ice cream (bacteria counts) 120 



Water 123 



Miscellaneous: 



Streptococci 2 



Throat swabs 25 



Paper 8 



Ice 16 



Total 1,187 



DEPARTMENT OF BOTANY 

 A. Vincent Osmun in Charge 



Effect of Soil Temperature on Gardenia. (L. H. Jones.) Low soil tempera- 

 tures induce a chlorosis of gardenia. A more intense form of the malady was 

 associated with a high level of soil nitrogen. Tests with diphenylamine on the 

 almost white leaves gave a strong positive reaction for nitrates, indicating the 

 inability of the leaves to utilize the nitrogen. 



In order to demonstrate that the effect of soil temperature on plants in the long 

 hot days of summer is similar to the effect obtained in late autumn, winter, and 

 early spring, a summer series of gardenia plants was set up in the soil temperature 

 apparatus. Chlorosis was obtained at the lower soil temperatures of 55° and 

 60° F. There was an absence of chlorosis at 65° F. and above. Associated with 

 the appearance of chlorosis was the setting of a great many flower buds, most 

 of them developing into good flowers. Although some growth took place at the 

 lower temperatures, it was very slow. There was no bud set at 65° F. and also 

 very little growth. With the soil temperature at 90° F., the growth was very 

 rapid, with large leaves and no bud set. 



It is thus apparent that soil temperature is a factor that not only controls the 

 color of gardenia plants, but also affects the physiological functions of vegetative 

 and flowering phases. The fact that chlorosis appears during the shorter days 

 of the year should not lead to the belief that lack of light is the responsible factor. 

 Any correlation that exists between length of day and chlorosis of gardenia is 

 apparent only when it is considered that length of day plays a considerable role 



