282 J. S. LAWRENCE AND W. W. FORD 



most difficult of all to clarify. Two organisms were originally 

 described by Gottheil as distinct species, regarded by Chester 

 however as practically identical. Strains of Bacillus simplex 

 and Bacillus cohaerens received by us from Krai were quite differ- 

 ent morphologically and while it is evident that we lack 

 many of those pronounced cultural and morphological re- 

 actions which render species and groups easy to recognize yet 

 we must not therefore place organisms together which are clearly 

 different. On one occasion we found in milk an organism evi- 

 dently identical with the strain of Bacillus cohaerens received 

 from Krai and corresponding to Gottheil's original description. 

 Subsequently this species was found five times by Dr. Laubach 

 in soil. These organisms gave us a fairly clear idea of the species 

 and its differentiation from Bacillus simplex whose description 

 we also give here. This latter description while made from a 

 strain isolated by Gottheil, applies also to a species subsequently 

 found in dust by Dr. Laubach. On two occasions we isolated 

 from milk the species described as Bacillus fusiformis by Gottheil. 

 Our isolations were identical with Gottheil's in every partic- 

 ular. Finally on one occasion we obtained a strain with prop- 

 erties practically the same as those of the species described by 

 Fliigge as No. XII and now known as Bacillus terminalis Migula. 



The 250 cultures studied were from 68 samples of milk, 12 

 of raw milk, 12 of milk pasteurized at 60°C., 32 of milk heated 

 to 85°C., and 12 of boiled milk. These cultures may thus be 

 held to represent so many various conditions in the development 

 of the bacteria of milk as to give an accurate idea of the spore- 

 bearing organisms of milk in Baltimore and they probably rep- 

 resent conditions met with elsewhere. By their combined 

 development in heated milk they give rise to the putrid decom- 

 position so frequently observed. As can be seen from their 

 cultural reactions these organisms are in the majority of instances 

 energetic protein-splitters and in practically every case rapidly 

 dissolve the casein in milk either before or after a preliminary 

 coagulation. 



After the various types of spore-bearing organisms were es- 

 tablished by the study of 250 cultures from the 68 samples 



