Aug. 19, 19221 THE BACTERIOPHAGE. [ MnlrcA^ Journal 



water of a series of tubes and floating this over the surface of the medium) 

 were left, the colonies, especially in the first dilution, soon started to turn 

 transparent, and the micrococci were replaced by fine granules. This action, 

 unlike an ordinary degenerative process, started from the edge of the colonies; 

 and further experiments showed that when a pure culture of the white or the 

 yellow micrococcus isolated from vaccinia is touched with a small portion of 

 one of the glassy colonies the growth at the point touched soon starts to 

 become transparent or glassy, sometimes killing out all the micrococci and 

 replacing these by fine granules. Experiments showed that the action is more 

 rapid and complete with vigorous growing young cultures than with old ones, 

 and there is very little action on dead cultures or on young cultures that have 

 been killed by heating to 60°C. 



Anaerobia does not favour the action, although it appears best in tubes 

 that are capped with gutta-percha tissue. The transparent growth when diluted 

 (one in a million) with water or saline was found to pass the finest porcelain 

 filters (Pasteur-Chamberland F. and B. and Doulton White) with ease, and 

 one drop of the filtrate pipetted over an agar tube was sufficient to make that 

 tube unsuitable for the growth of the micrococcus— that is, if the micrococcus 

 was inoculated down the tube as a streak, this would start to grow, but would 

 soon become dotted with transparent points which would rapidly extend over 

 most of the growth. The number of points from which this starts depends 

 upon the dilution of the transparent material, and in some cases it is so active 

 that the growth is stopped and turned transparent almost directly it starts. 

 This condition or disease of the micrococcus when transmitted to pure cultures 

 of the micrococcus can be conveyed to fresh cultures for an indefinite number 

 of generations; but the transparent material will not grow by itself on any 

 medium. 



If in an infected tube small areas of micrococci are left— and this usually 

 happens when the micrococcus has grown well before becoming infected— 

 these areas will start to grow again and extend over the transparent portions, 

 which shows that the action of the transparent material is stopped or hindered 

 in an overgrown tube; but it is not dead, for if a minute portion be transferred 

 to another young culture of the micrococcus it soon starts to dissolve up the 

 micrococci again. Although the transparent material shows no evidence of 

 growth when placed on a fresh agar tube without micrococci, it will retain 

 its power of activity for over six months. It also retains its activity when made 

 into an emulsion and heated to 52° C, but when heated to 60° C. for an hour 

 it appears to be destroyed. It has some action, but very much less on 

 Staphylococcus aureus and alhus isolated from boils of man, and it appears to 

 have no action on members of the coU group or on streptococci, tuberc'e bacilli, 

 yeasts, etc. The transparent material was inoculated into various animals, and 

 was rubbed into the scratched skin of guinea-pigs, rabbits, a calf, a monkey, 

 and a man, bat all the results were negative. 



When continuing my investigation of infantile diarrhoea and vomiting, for 



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