40 VARIATIONS IN MORPHOLOGY [ch. iv 



in the living tissues show branching filaments and "clubbing" 

 (ibid.). 



The Kld)s-Loeffler bacillus in young cultures, on serum and 

 agar-agar, likewise shows clubbed and branched forms. 



The bacillus of anthrax, both on artificial media and in the 

 living tissues, forms leptothrix-like chains or filaments. These 

 may be observed in a three hours' culture of the bacillus in 

 a drop of aqueous humour (Marshall Ward and Blackman, 

 1910). 



Adami (1892) describes B. typhosus as forming long fila- 

 ments when grown on potato. Many observers have recorded 

 the same phenomenon in cultures of B. coK. For example, 

 Ohlmacher (1902), Revis (1908) and Wilson (1908) isolated 

 leptothrix forms of B. coli from the heart's blood in a case 

 of septicaemia, from milk and from urine respectively, the 

 organism in each case forming a dense network of branching 

 filaments. 



Ritchie (1910) isolated leptothrix forms of B. inflvsnzae 

 from the cerebrospinal fiuid in certain cases of meningitis, and 

 similar forms of the "pseudo-infiuenza" bacillus from the lung 

 in pneumonia. The causal factor in two of these instances — 

 B. coli isolated from urine and B. influenzae from the spinal 

 fluid in meningitis — was probably the presence, in both these 

 fluids, of urea. Connal (1910) showed that in meningitis the 

 spinal fluid may contain as much as "5 per cent, of urea, and 

 Wilson (1906) showed that urea provokes the development of 

 leptothrix forms in many organisms. 



II. ZooGLEic Forms artificially produced. 



1. The addition of various chemical substances to the 

 culture medium in which an organism grows, leads to the 

 development in many cases of leptothrix forms. 



Peju and Rajat (quoted by Wilson, 1910) observed that 

 salts, and Almquist (ibid.) noted that sewage, had this efiect on 

 B. typhosus. Walker and Murray (1904) showed that certain 

 dyes, particularly methyl violet, had the same action on 

 B. typhosus, B. coli and the cholera organism. Wilson (1906), 

 by adding urea to the culture media, obtained leptothrix forms 



