426 C. CLIFFORD DOBELL. 



2. Bacillar Forms. 



Im two previous jiapers (Dobell, 1908, 11*09), I have given a 

 description of the structui-e and method of spore-formation in 

 two laro-e Bacteria which I obtained from the large intestines 

 of frogs and toads. These two forms I named Bacillus 

 flexilis and Bacillus spirogyra. The former is charac- 

 terised by liaving a nucleus in the form of chromidia scattered 

 through the cytoplasm : the latter by having a nucleus in the 

 form of a spiral or zig-zag filament. B. flexilis, moreover, 

 is a very large, flexible organism and forms two spores : 

 whei'eas B. spirogyra is considerably smaller, rigid, and 

 forms a single spore. As most of tlie Bacilli which I am 

 now about to describe are organised in a manner similar to 

 that of these forms, I shall — for convenience — refer to them 

 frequently as Bacilli of the flexilis type or spirogyra 

 type; meaning thereby that the organisms under discussion 

 are structurally similar to one of these forms, though implying 

 nothing as regards difference or identity of species. 



(a) Bacilli of the flexilis Type. 



(1) Bacillus flexilis. — Although I have already given a 

 detailed account of this organism (Dobell, 1908), I shall here 

 add a few further observations on its structure, as it seems to 

 me of considerable importance that its cytology should be 

 made absolutely certain. 



M}^ original figures were drawn from preparations stained 

 by Giemsa's method. The various modifications of this 

 method which I employed I have already given — as also 

 several other methods which gave me satisfactory^ results. I 

 would here emphasise the fact that all niethods which give 

 reliable cytological results reveal exii(;tly the same structure 

 in this organism. They show a number of deeply staining 

 granules scattered through the cytoplasm — an appearance 

 which I have interpreted as a nucleus in the form of 

 chromidia. Subsequent work on this and allied forms has 

 convinced me of the correctness of this interpretation. 



