ANNUAL REPORT, 1947-48 35 



Curves plotted for each of the three organisms show the relationship between 

 the plate count and turbidity value as measured by the spectrophotometer. 

 Results indicate that suspensions of non-sporeforming organisms can be standard- 

 ized to a reasonably accurate number by the use of transmission curves. Results 

 with B. cereiis were doubtful; therefore standardization of spore suspensions by 

 the use of the homogenizer and spectrophotometer cannot be recommended at 

 the present time. 



2. New Developments in Sanitizing Teat Cups Between Cows Milked. (W. S. 

 Mueller and D. B. Seeley.) The method commonly used today for sanitizing 

 teat cups between cows milked is ineffective because contact with the germicide 

 is too short. This is a major cause for the spread of mastitis from an infected to 

 a non-infected udder. 



As a result of this study, a new method for sanitizing teat cups has been de- 

 veloped, in which the basic idea is the use of an extra milking-head assembly', 

 thus making it possible to keep the teat cups in the germicidal solution for two 

 minutes or more without increasing the milking time for the herd. This markedly 

 reduced the total bacterial counts of the teat cup and under laboratory condi- 

 tions killed almost all of the S. agalactiae organisms, which are chiefly responsible 

 for mastitis due to infection. 



From this study it is concluded that the new method of sanitizing teat cups 

 between cows milked greatly reduces the chance of spreading mastitis through 

 the herd, without increasing milking time or interfering with barn routine. 



3. Effect of Some Water Constituents on Quaternaries. (W. S. Mueller and D. B,. 

 Seeley.) While "hard waters" have been reported to be incompatible with 

 quaternaries, it seemed desirable to have more information on the effect of each 

 of the many constituents normally found in potable waters. The germicidal 

 potency of an alkyl-dimethyl-benzyl-ammonium chloride was tested against 

 E. coli, and the tentative conclusions are as follows: 



a. There was no direct correlation between water hardness as measured by 

 the soap method and the germicidal potency of the quaternary solution. 



b. The following ions had no adverse effect on the germicidal potency of the 

 quaternary: cations — -potassium, sodium, and lithium; anions — -chloride, sul- 

 fates, and nitrates. 



c. The following cations when present in sufficient quantities reduced the 

 effectiveness of the quaternary: calcium, magnesium, and bivalent and trivalent 

 ionized iron. Calcium and magnesium acted alike; trivalent ionized iron was 

 far more detrimental than bivalent ionized iron. 



d. A 200 p.p.m. solution of the quaternary studied had sufficient germicidal 

 potency to do most sanitizing jobs even when the concentration of calcium plus 

 magnesium was as much as 600 p.p.m. 



e. A 200 p.p.m. solution of the quaternary was completely inactivated by 

 10 p.p.m. of trivalent ionized iron. 



DEPARTMENT OF ECONOMICS 

 Philip L. Gamble in Charge 



Transfer of Ownership and Its Effect on Agricultural Land Utilization. (David 

 Rozman.) Work on this project has proceeded with the examination of records 

 obtained in agricultural communities in several parts of the State. The Registry 

 of Deeds and assessors' records have provided the basis for a complete list of 

 land transfers in the selected areas, from the beginning of 1940. The towns 



