BV R. GREIG-SMITH. 



109 



A till of milk which had been made after the supposed fault 

 ill the condensing apparatus had been remedied and which was 

 said to be capable of standing prolonged incubation without 

 change, was placed in the incubator for ten days. Upon opening 

 the tin and examining the milk, a considerable number of small 

 blobs of jelly were found distributed throughout the milk. 

 These blobs contained tlie micrococcus. It is therefore evident 

 that the infection and subsequent alteration of the milk had 

 little if anything to do with the entry of water containing 

 calcium and magnesium salts in solution. 



The micrococcus was obtained in pure culture by plate-cultiva- 

 tion and its bacterioscopic characters were noted. With the pure 

 culture several experiments were made. In one of these, por- 

 tions of approximately 25 c.c. of ISTestle's condensed milk, which 

 keeps well in this climate, were transferred into a series of sterile 

 flasks. Two of these had 0*0025 grm. of chalk added, and all 

 were heated in a water-bath at 60° for an hour. The flasks were 

 then infected, covered with rubber-caps, and placed in an incu- 

 bator at 37°. 



milk (control) 



,, + coccus 



,, ,, +B. acidi lactici 



,, + chalk (control) • 



+ coccus 



11 days. 



no change 

 thickened 



19 days at 37°. 



no change 



very much thickened 



no change no change 



very much thickened coagulated 



The experiment clearly shows that the coagulation of the milk 

 is brought about by the micrococcus and that the alteration can 

 be assisted by small quantities of calcium carbonate. 



A repetition of the experiment, using Nestle's milk which had 

 been heated for six hours in its tin at 60,° was made. 



•milk (control) 

 ,, + coccus 



chalk (control) 



14 days. 



no change 

 much thickened 



no change 

 much thickened 



I 27 days at 37°. 



I no change 



I very much thickened 



I 



' no change 

 very much thickene 



