154 Journal of Agricultural Research voi. vi. no. 4 



of the species used produced visible growth except upon or near the sur- 

 face of the milk. Observations of growth must include, therefore, the 

 surface of the milk and especially the glass from the surface of the milk 

 upward for a few millimeters, since most molds begin to grow first upon 

 the glass. When no spores occurred upon the glass a free-fioating colony 

 in one case escaped observation until it fruited. 



The inoculated milk tubes, with the exception of the control tubes, 

 were heated in a water bath in which the water was agitated and the tem- 

 perature of the milk was recorded in a control tube by a thermometer 

 placed in the milk. The temperature in the tubes was not allowed to 

 vary more than half a degree in either direction. The results of the exper- 

 iments with the holder process are shown in Table I. In preparing this 

 table the records of the checks, or unheated tubes, of successive exper- 

 iments were found sufficiently uniform to permit them to be averaged 

 and appear but once. Experimental tubes were made in duplicate; and 

 when the results were not reasonably harmonious the work was repeated. 

 Table I summarizes the tabulated data from a series of experiments 

 extending over a period of several months. 



