ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 91 



Oscillatorieae is mixed with phycocyanin, while that of the Bacteriaceae 

 is normal chlorophyll. Furthermore, the mode of formation of the 

 reproductive cells is quite different. In the Oscillatoriese it is simple 

 vegetative cells which become slightly transformed by a change in the 

 cell-contents, and a slight thickening of the cell- wall, thus producing 

 permanent cells rather than spores. In the Bacteriaceae, on the con- 

 trary, the true spores are special bodies, of endogenous origin, and 

 differing greatly in their form and properties from the ordinary 

 vegetative cells. The facts above detailed seem to the author rather 

 to confirm the distinction between the two families, than to tend to 

 unite them. 



Blue Milk.* — The spontaneous production of blue milk is said by 

 F. Neelsen to be confined to a certain district of the German shores of 

 the Baltic. The production of the blue colour is always accompanied 

 by an evolution of carbonic acid, often in great quantities. The 

 colouring matter has nothing to do with any bacteria, but is dissolved 

 in the serum of the milk. It appears to be nearly related to aniline- 

 dye. There is no foundation for the idea that blue milk is 

 poisonous. 



Neelsen determined the presence in blue milk of bacteria in the 

 form of rods with rounded ends, having a length of 2 • 5-3 • 5 jx, not 

 always straight, but often curved in various ways. In an early stage 

 they move about with great activity, as if by the aid of cilia, which, 

 however, have never been detected. At a later period, as the milk 

 becomes more blue, they divide by abstriction, ending in the produc- 

 tion of torula-like chains, which gradually become stationary. The 

 separate cells of these chains are conidia, which germinate in fresh 

 but not in the same milk. These sometimes become aggregated and 

 enveloped in a common mucilaginous envelope, assuming the gloeo- 

 bacterial form. Placed in Cohn's nutrient fluid, they produce true 

 spores by the swelling up of a portion of a rod, which germinate 

 like the conidia. In potassium nitrate leptothrix-like filaments were 

 obtained. 



Mitigation of Fowl-Cholera Poison.t — To obtain the poison in 

 its most virulent form, M. Pasteur states, it should be taken from a fowl 

 which has died, not of acute but of chronic disease. On cultivating 

 this in several solutions of fowl-broth by transferring it in succession 

 from one to the other, it is found that it suffers no diminution of its 

 virulence in the passage. However, experiments made by varying the 

 length of the periods of time during which the solutions are left 

 intact after having the parasite added to them, show that the time 

 allowed for its development is an important element in the question. 

 Thus, with intervals of only from one day to two months between any 

 two successive inoculations of the solutions, no modification of their 

 virulence is experienced, though in proportion as the interval is in- 

 creased, signs of such a modification appear in the slowness with which 



* Cohn's Beitr. Biol. Pflanzen, iii. (18S0) pp. 187-246. 

 t Comptes Eendus, xci. (1880) pp. 673-80. 



