106 CHROMOPAHorS HACTKKIA 



and which tilled the credulous mind of the masses with horror ; and even in 1819 

 the entire province of Padua was set in a commotion by the frequent appearance 

 of such spots and drops on various articles of food. This red, slimy coating 

 was examined by SETTE (I.), who recognised it as endowed with vitality and 

 named it Zin> : /'t/'t,-tina imetrofa. A small quantity applied to still unaltered 

 food-stuffs, tfcc., sufficed to produce red spots on those latter. This phenomenon 

 was first more closely investigated in 1848, when it was of frequent occurrence 

 in Berlin. Cli. Ehrenberg studied the spots and drops, and found them to consist 

 of minute oval cells 0.5 to i.o /i in length ; and bearing in mind their form and 

 observed powers of locomotion, he classified this wonderful organism as a new 

 species of his genus Afo/ntn. and called it Monas prodigiosa, a designation subse- 

 quently changed by Cohn to Aficrococcuft jtr<,fH;/io8us. As this microbe (mostly 

 appearing as approximately spherical cells) will, under certain conditions of environ- 

 ment, assume an elongated form, it is also frequently named both Bacterium 

 prodigiobum and Bacillus pwtKffiowtf, as was done by Fliigge in his handbook. 

 These names, therefore, indicate one and the same species of fission fungus, and 

 are also synonymous with the older names Palmella prodigiosa and Bactcridium 



This fission fungus excretes a peptonising enzyme, and consequently liquefies 

 the gelatin medium. A temperature of 25 C. is the most favourable one for 

 its growth, and it thrives most luxuriantly on boiled potatoes, the formation of 

 trimethylamine becoming at the same time apparent. Starch paste, boiled rice, 

 boiled egg-albumen, boiled carrots, boiled meat, milk, and many other food-stuff's, 

 form suitable media for this microbe, which, however, will not develop on raw 

 potatoes, raw meat, or uncooked steeped rice. It is therefore evidently a true 

 saprophyte, occurring only in defunct or destroyed and converted nutrient media. 

 When cultivated in thinly fluid solutions it exhibits- -as was established by 

 SCHOTTELIUS (I.) brisk powers of locomotion. 



The red colouring matter, which is produced in presence of air only, is, 

 according to the researches of this observer, at first diffusely distributed through 

 the young cells. It is then excreted, and collects into various-sized granules 

 which lie between the cells and so impart a red coloration to the culture. The 

 tone of the colour changes with the age of the culture, beginning as a pale rose 

 and passing through a bright scarlet stage into dark brown-red. According to 

 the researches of J. SCHROETER (I.) and SCIIEURLEN (III.), the colouring matter 

 is insoluble in water, but readily soluble in alcohol, xylene, chloroform, carbon 

 bisulphide, and, to a slighter extent, also in ether and in fats (e.g. olive oil). 

 The alcoholic solution exhibits in the spectroscope three absorption bands : one 

 beyond D, the second just before E, and the third before F. The elementary 

 formula was determined by A. B. GRIFFITHS (I.) as C 38 H. 6 NO., though the 

 analytical results obtained by Scheurlen are not in conformity therewith. The 

 opinion expressed by O. ERDMANN (I.) that the colouring matter generated by 

 M. jtrodigio8U8 is identical with t'uchsine has been contradicted by OTTO 



HKI..M (I.) and r.HDOXI-UFFREDUZZI (I.). 



This fission fungus forms a very suitable object for the study of mutability. 



K. WASSERZUG (I.) traced the changes of form which this species underwent 



in consequence of alterations of the conditions of nutrition. By repeated 



cultivation on faintly acid media 0.3 to 0.4 grin, of tartaric acid per litre 



cultures are obtained the cells of which are no longer globular or oval, but 



exhibit the form of actively motile long rods and threads ; the modifications 



being the more pronounced as the number of inoculations is increased. As soon, 



however, as an inoculation is made from such acid liquids into an alkaline 



ium, the typical short cells reappear. This reversion also occurs when the 



remain for some time in the original acid medium, after the reaction has 



