274 J. S. LAWRENCE AND W. W. FORD 



soil and the lactic acid bacteria in milk. In consequence the 

 bacteria found in nature which seem to be lacking in any 

 definite function have been largely neglected. At various times 

 many species of spore-bearing organisms have been described 

 and recorded in the literature and in many instances these 

 cultures have been kept alive in laboratories both in Europe 

 and in America. It would seem an easy task therefore to collect 

 the spore-bearing bacteria from different institutions, make a 

 careful study of their properties and arrive at some conclusion 

 as to their identity and classification, just as is done with the 

 pathogenic species. This method of solving the difficulty is 

 open to serious objections, however, and has not thus far proved 

 of great value. In the first place the descriptions originally 

 given of many of these species are meager and the original 

 cultures have not been saved. In consequence the literature 

 of bacteriology is thickly strewn with names of spore-bearing 

 organisms which have absolutely no meaning. The term 

 Bacillus suhtilis for instance is applied to almost any large 

 microorganism which forms spores readily and grows abundantly 

 on artificial media, and cultures identified as Bacillus subtilis 

 by different bacteriologists are often found to have little or 

 nothing in common. Again the cultures which have been kept 

 alive have in many instances so changed in character as no longer 

 to give the reactions orginally described. Thus Migula (1897) 

 found that of some six hundred cultures obtained by him from 

 the laboratories in Germany only a small number had the 

 characteristics first ascribed to them. Finally, pure strains of 

 spore-bearing bacteria are more difficult to keep in direct descent 

 in the laboratory than are other species. When cultures become 

 contaminated it frequently happens that the contaminating 

 species is picked up from the plates made to purify the strain 

 and carried on as the original. This has happened a number of 

 times in our own laboratory during the past few years and in 

 consequence we have become very sceptical of the value of any 

 conclusions based upon a comparison of existing stock cultures. 

 A number of years ago an attempt was made, in the laboratory 

 of Dr. Adami in Montreal (Ford, 1903) to separate and classify 



