276 J. S. LAWRENCE AND W. W. FORD 



water, intestinal contents and contaminated plates. From this 

 number we have obtained 28 distinct types of which 22 are 

 clearly to be identified as well known species, 2 are distinct 

 varieties of old types and 4 are evidently new species. In general 

 our aim has been to clarify our knowledge in regard to old species 

 and not to establish new types except when our isolations showed 

 certain characteristics not already referred to in the literature 

 and of distinguishing importance. 



The media employed in this work were the standard media 

 of the laboratory. A great deal of emphasis was laid upon the 

 reactions with gelatin, with litmus milk, with glucose, saccharose, 

 and lactose broth, with glucose htmus agar and with Loeffler's 

 blood serum. The morphology was studied from smears made 

 from plain and glucose agar cultures 6 to 8 hours old and 22 to 

 24 hours old, and from cultures 1 to 2 weeks old, the organisms 

 being always stained with Gentian violet. The same preparations 

 were used later for measurements and for illustrations. The 

 method of sporulation and the size, shape and position of the 

 spore were observed with great care. A study of the spore wall, 

 and its differentiation into the exine and intine of Gottheil and 

 Chester, while interesting and important, proved of little help 

 in classification. The method of spore-germination was like- 

 wise found relatively valueless. Nearly every type of spore- 

 germination could eventually be found with most species and 

 our observations were so inconstant as not to furnish any basis 

 for classification. Micro-chemical reactions, while undoubtedly 

 of great value, could not be worked out with any degree of 

 thoroughness and were eventually discarded. Careful obser- 

 vations were made upon the thermal death points which were 

 established with broth cultures subjected to various degrees of 

 temperature in the Arnold sterilizer and in the autoclave. In 

 general our classification may be said to rest upon morphological 

 and tinctorial properties, spore-formation and cultural reactions. 

 How valuable our results are can only be determined by the 

 extent to which other workers may be able to utilize this classi- 

 fication in subsequent investigations. 



