DR PARK'S EXPERIMENTS 



129 



in 1900. Park's record was published in 1901.^ Our investigation 

 has not hitherto been published. 



The following figures obtained by Park show the development 

 of bacteria in two samples of milk maintained at different tem- 

 peratures for twenty-four, forty-eight, and ninety-six hours respec- 

 tively. The first sample was obtained under the best conditions 

 possible, the second in the usual way (the figures of this sample are 

 underlined). When received. Specimen No. i contained 3000 

 bacteria per c.c, and Specimen No. 2, 30,000 per c.c. 



We have selected this experiment of Park for comparative pur- 

 poses on account of its fulness of detail, although it differs in im- 

 portant particulars from our own results which were arrived at two 

 years previously. We have, for convenience, inserted the tempera- 

 tures in degrees centigrade. The table should, of course, be read 

 downwards to observe the effect of temperature, and across for the 

 effect of time. The cultures were made on agar in Petri dishes.- 



There are two points upon which we may remark. First, it 

 may be noted that at 32° F. (o' C.) there is a decline in the number 



1 Jour, of Hygiene, 1901 (July), p. 398. 



^ The agar used by Park contained 2 per cent, peptone, and i-2 per cent 

 agar, and was faintly alkaline to litmus. 



