ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 615 



The various strains of B. violaceus differed in the intensity of the pig- 

 ment produced, but presented little niorpliological variation. The 

 organism is motile, Gram-negative, and does not form spares. Bacillus 

 membranaceus amethystinus is closely allied ; pigment-formation is slower 

 and never so well-marked. A comparison of the cultural, morphological, 

 and serological characters of the twenty-two strains investigated is 

 given in tabular form. 



Action of Bacteria on Coloured Media.* — H. F. Smyth has in- 

 vestigated the effects of the growth of certain vibrios and coliform 

 organisms upon dahlia-agar (nutrient agar coloured with 1 p.c. dahha 

 solution). iSignorelli in a previous paper claimed that this medium was 

 of value in the identification of cholera vibrios, stating that these 

 organisms grow well on the medium, become deeply stained, and produce 

 progressive decolorisation of the medium, whereas other organisms 

 produce no such decolorisation. Siguorelli attributed this absorption 

 of the dye to a selective affinity of certain organisms for the dye, and 

 claims that the decolorisation is due to physical abstraction of colour 

 from the medium by the organisms, and not to any chemical reaction. 

 The author of the present communication shows that most organisms 

 which produce alkali on agar will decolorise dahlia ; that this effect is 

 due to the presence of alkali, and is inhibited by acid-production ; that 

 dahlia-agar decolorised by bacterial action can have its colour restored 

 by treatment with acids ; that many organisms grow vigorously on 

 dahlia-agar, decolorising the medium ; and therefore the method is of 

 no value for the identification of cholera vibrios. 



Morphology of Glanders Bacillus. f — M. Carpano has made a 

 study of the morphological characters of B. mallei as it is found in the 

 animal body, as well as in artificial culture. Pleomorphism is very 

 marked. Threads with spindle-shaped or bulbous ends are frequently 

 found in cultures. These have hitherto been regarded as involution 

 forms, but the author regards them as active, readily transplantable, 

 and probably highly virulent. From an infected guinea-pig there were 

 recovered granular forms, simple bacilli, massed aggregations of bacilli, 

 filaments, spindles, and other varieties. Certain preparations show 

 capsules and spores. True branching was not observed. On these 

 grounds the author assigns this organism to the family Trichomycetes, 

 genus Leptothrix. 



Bacillus salmonicida.J— J. W. Fehlmann has investigated this 

 organism, the causal agent of salmon-disease. He describes the bacillus 

 ag a flagellate, non-motile organism, which acquires the property of 

 motility on certain culture media. On fish-agar, and to a certain extent 

 on ordinary feebly-alkahne agar, cultures of the organism develop a 

 brown pigment. Fish may be infected by subcutaneous, intramuscular, 

 or intraperitoneal infection. The organism is also pathogenic for 

 certain warm-blooded animals, such as rabbits and guinea-pigs. Most 

 of the observations of this author confirm those of previous workers on 

 this subject. 



* Centralbl. Bakt., Ite Abt. Orig., Ixxi. (1913) pp. 319-22. 

 t Centralbl. Bakt., Ite Abt. Orig., Ixxi. (1913) pp. 267-85. 

 X Centralbl. Bakt., Ite Abt. Orig., Ixxi. (1913) pp. 384-407. 



