XVI] VIBRIO AND SPIRILLUM 467 



has shown that, unlike other bacteria, they are barren of a 

 ceUulose sheath, since dilute liquor potassae dissolves the 

 whole substance of the spirilla. By drying and staining 

 cover-glass specimens it has been shown that the spirilla are 

 uniform spirals, and do not show anything that might be 

 interpreted as being made up of shorter elements, comma 

 bacilli or vibrios. The spirals when long are often plicated, 

 but their turns are always close, and more or less in the 

 manner of a corkscrew. Immediately preceding the febrile 

 stage they appear in the blood, grow more and more numer- 

 ous during the fever, and disappear again completely from 

 the circulating blood before the fever quite ceases. During 

 the non-febrile stage they most probably are present in the 

 spleen and marrow of bone — Birch-Hirschfeld found many 

 of them in the necrotic foci of the spleen — where perhaps 

 they undergo germination and reproduction. It is feasible 

 to assume that when during the febrile stage they reach the 

 acme of their development they gradually break down, 

 leaving spores in the shape of granules behind : these are 

 carried into the spleen and bone marrow where they accu- 

 mulate. During the non-febrile stage these spores germinate 

 here again and gradually grow into the spirilla, which when 

 ripe and motile gradually find their way again into the blood. 

 Such a view would well harmonise with the facts of the case 

 and also with what has been shown of the Plasmodium 

 malarise. 



As a matter of fact the spirilla in the blood often show 

 bright granules in their interior, which might well be spores. 



Koch has shown that in artificial culture the spirilla are 

 capable of growing out into long spiral filaments matted 

 together, but no real artificial cultures have been as yet pro- 

 duced. That the spirilla are the real microbes of relapsing 

 fever is proved by the experiments of Vandyke Carter 



