>37 
Nov. i, 1S85.] The Australasian Scientific Magazine. 
to enquiries on the same lines with regard to other fermentations. When 
milk turns sour the sugar of milk which it contains is converted into an 
acid, and in 1780 Scheele gave to it the name lactic acid. As a chemical 
product it was well known, and much attention has been given to it 
from the chemical point of view. In 1857 Pasteur wrote his celebrated 
“ Memoire, Sur la Fermentation apelli Lactique and this, more than 
anything else, gave an impetus to the study of what is now known as the 
“ germ theory” of fermentation. This was followed up by his papers on 
alcoholic fermentation. He distinctly showed the ferments to be organised 
living bodies. Microscopes now are in everybody’s hands, and it is easy 
to see the life forms on which Pasteur has written so much, and on which 
there has been such a storm of controversy as to whether they originate 
spontaneously or not. The war over, “ the beginnings of life” has enveloped 
the subject with a keen interest for many it, perhaps, would not otherwise 
have had. Future generations may wonder that theological journals 
should have so warmly taken up the processes of the souring of milk and 
the brewing of beer, and will admire the calm patience with which men 
like Lister, Dallinger and Tyndall pursued their tedious and accurate 
researches on supposed spontaneous generation, heedless of the outside din. 
One practical outcome of the fray has been that the whole subject has re- 
ceived such a scrutiny that accurate knowledge has been considerably 
advanced. While it has been well established that there is no proof that 
these low vegetable or animal forms ever do originate spontaneously, 
their life histories have also been learnt. To see the vegetable forms 
which bring about changes in milk is but little trouble. Let some milk 
be exposed to the air. In a short time it will turn putrid 01 sour, and 
after a while will separate, as blood separates into clot and serum. It a 
drop of this milk be placed under a powerful microscope, movements will 
be seen due to a vibrio, and a careful watching will detect a minute 
Bacterium, as it is now called. The naming of these low forms has 
undergone several changes, and the position assigned to them has varied. 
They are now, however, ranked with the fungi in a separate group— -the 
Schizomycetes. Based on differences of their shape they are divided into 
(1) Bacteria proper, oval or slightly elongated; (a) Bacilli, rod-shaped ; 
(3) Micrococci, round ; and (4) Spirochcetie spiral. Micrococci are frequently 
fonnd in milk, but apparently produce no change. A Bacillus (some- 
times called Bacillus syncyanum ) produces the blue colour in sour milk. 
Bacterium lactis is the cause of lactic fermentation. 1 his last was made 
known and named by Professor (now Sir) Joseph Lister, who observed it in 
the course of the studies which he undertook in reference to “ germs ” in 
their relation to wounds and surgical operations. Ihc convenient term 
micro-organism includes all the forms, whether producing glanders, 
tubercle, enteric fever, fowl cholera, or fermentation, etc. One of the 
most important branches of modern research is the “cultivation” of micro- 
organisms under circumstances so that their whole life-history can be 
watched, an excellent illustration of which was given during the Health 
Exhibition, in the biological laboratory, under the charge of Dr. Watson 
Cheyne. Thus, among many “ cultivations ” which have been effected, 
it has been found that Bacterium lactis can be grown pure in other 
solutions besides milk, and when inoculated into milk this 
becomes sour, and coagulates from the formation of lactic 
acid from the milk suger. A still more interesting point has been 
proved, which may some day come to have important practical bearings. 
