489 
to subject the latter to a slightly higher temperature, viz., 66° to 
70° C. (151° to 160° F.) for two or three minutes. The tempera- 
ture at which these micro-organisms perish is called the “death 
point” of these microbes. 
The micro-organisms causing diseases of wines are more micro- 
scopic than the yeast plant, and can only be seen under a magnify- 
ing power of 600 to 900 diameters. Each kind presents under the 
microscope well-defined appearance, and each one affects the wine 
in a different manner. It is not the microbe itself that imparts to 
the affected wine the defects which shows it to be diseased, but 
rather the products consequent on its work in the medium in which 
the microbe lives. It is therefore important that either as a pre- 
ventive measure or as a curative treatment, if the disease is not too 
far advanced, timely measures be taken for removing the cause of 
the trouble. As demonstrated by Pasteur, heat under proper con- 
trol does this without impairing the quality of the wine. 
In a substance like milk, on the other hand, which is at the same 
time alkaline and fatty, the temperature has to be raised to about 
110° C. or ever higher to sterilise the liquid, which has to be brought 
to the boil. 
When Pasteur was carrying out his experiments on the heating 
of wines, a commission was appointed to taste the wines so treated, 
and the members reported as follows :— 
“Tt is impossible to deny that the result of heating the wines 
examined shows a decided advantage over the unpasteurised wines. 
Its effect is preventive of disease, it destroys the germs; the pre- 
sence of which is the cause of the various sickness in wine— 
without hindering the development of their quality. All the pas- 
teurised wines are good; they have not changed in taste or colour; 
their condition is perfect. We have come to the conclusion that 
the process is of practical value, and especially when applied to 
large quantities of wine.” 
When pasteurising wine, or for the matter of that, any kind 
of liquid, it is essential that everything which comes in contact with 
it must be sterilised, otherwise infection may again take place, and 
the whole work is in vain. 
Unless sufficient tannin is present, it may assume a light bluish 
tint after heating, and if it is intended to blend two or more wines, 
it is advisable to pasteurise before than after the blending. It is 
needless to say that an unpasteurised wine should not be used for 
filling up casks of pasteurised wines. 
DiseasE GERMS. 
The micro-organisms, which are the active agents of diseases 
of wine, have been divided by Pasteur in two classes :— 
(1) Those which take the oxygen they need for their respir- 
ation from the air itself, called “aerobic” ferments. 
