The Fermentations of Milk. 
805 
in milk, and occasionally invade it. Two species of bacillus are 
known which turn milk violet, several which turn it yellow, and 
some which produce a green colour. A large number of organisms 
have been described which turn milk various shades of red, some 
curdling it and some not. In addition to these the well-known 
Micrococcus prodigiosus, the cause of “ bloody snow ” and “ bloody 
bread,” occasionally grows on the surface of milk or cream, pro- 
ducing bright- red spots. 
Slimy, viscous, or ropy milk is not uncommonly met with. Tlie 
popular explanation of this, as arising from food eaten by the cows, 
is superseded by the discovery by various observers of no less than 
eighteen distinct organisms which, when inoculated into milk, 
render it more or less viscous. About half of these have been 
isolated from milk itself, the others from vai’ious sources, such as 
cheese, wine, beer-wort, water, inflamed udders, itc. The viscosity 
produced varies from a slight thickening to a solidification whicli 
allows the vessel of milk to be inverted without spilling its contents. 
In some cases so tenacious is the mass that it can be drawn into 
threads many feet in length. The slimy substance is no doubt 
difierent in diflerent cases, and the by-products of the various 
fermentations also are very various. A viscous fermentation, 
similar to some of those that can be set up in milk, is known to 
occur rather frequently in wine and beer. 
In at least two instances viscous milk is turned to useful 
account, and these varieties may be considered normal products. 
In Norway, Sweden, and Lapland the people produce slimy milk as 
an article of diet. This they sometimes do by feeding the cows with 
the little plant ^ called Pinguicula vulgaris, but the true rationale of 
the process becomes apparent when we are told that they effect the 
same object by rubbing the milk vessels with this plant or by im- 
mersing it in the milk. When a taint is communicated to milk by 
a particular food it is generally due to the fact of the milkers 
handling the food in feeding the cows, and not to the fact of the 
cows eating it. A familiar instance of this is furnished by silage, 
which earned a bad name as a food for milch cows before the proper 
' The Common Butterwort {Pinguicula vulgaris, L.) is a native British 
plant. It grows in wet or boggy situations, and is fairly common in the western 
hilly districts of England, Scotland, and Ireland, but is rarer in other parts of 
the kingdom. It has a rosette of spreading leaves, of a light-green colour, some- 
what succulent in texture, and presenting a wet, clammy appearance. The 
flower stalks are 4 to 6 inches high, and each bears a solitary flower, two-lipped, 
bluish-purple, and spurred. The plant is in flower from April or May to July, 
and its fruit is a capsule, as shown on the left-hand side of the illustration 
(p. 806). It is a perennial. The name Pinguicula is derived from the Latin 
pinguis, in allusion to the greasy texture of the plant. There are two or three 
other native species of Pinguicula, including the Alpine Butterwort {P. alpina, 
L.) and the Pale Butterwort {P. lusitatiica, L.) ; and these, with three or four 
species of Bladderwort (Utricularia), make up the small natural order Lenti- 
bularineae, the nearest affinities of which are with the primrose and foxglove 
families. —Ed. 
