INVEETEBRATA, CRYPTOGAMIA, MICROSCOPY, ETC. 603 



for many hours a temperature of 100^ C. In infusions of yeast or 

 hay they may resist for five hours, whilst in distilled water they are 

 killed by two or three houi's' boiling. A temperature of 115^ kills 

 them very rapidly. 



4th. When boiled for a few minutes in a slightly acid mediimi 

 these spores are not killed, for they develop when the liquids are 

 placed in sterile neutral media. 



5th. A temperature of 40^ seems most favourable to the growth of 

 these organisms, though they still develop at 50^. 



Whilst pursuing these researches he encountered another organism, 

 also a Bacillus, which is both aerobian and anaerobian. When in 

 air it absorbs oxygen from it, but in vacuo it acts as a ferment, and 

 disengages a mixture of carbonic acid and hydrogen ; thus resembling 

 the yeast of beer. 



It develops also in neutral or slightly alkaline media, and not at 

 all in very acid liquids. 



Its germs or spores resist a temperature of 100°, but for a much 

 shorter time than the spores of Bacillus suhtilis. In distilled water 

 at 100° they resist for thirty minutes, but are killed in forty minutes. 



Like Bacillus suhtilis, the spores are not killed when sown in 

 slightly acid liquids and boiled for some minutes. 



The temperature most favourable to their development is that 

 which suits Bacillus suhtilis. 



The liquids in which the new Bacillus multiplies become distinctly 

 acid, whereas Bacillus suhtilis produces no change. 



These results lead to important conclusions. 



1st. The boiling of water in an apparatus for some minutes, and 

 even for more than an hour, may not be sufficient to deprive it of all 

 living germs, since the germs of the organisms here referred to are 

 found in ordinary water, although in variable proportions. 



2nd. In manipulating neutral or slightly alkaline organic liquids 

 the apparatus used must have been previously subjected to a very 

 high temperature. 



It is doubtless because apparatus was made use of which it was 

 believed was freed from germs merely by the boiling of the water, 

 that natural milk fresh from the cow's udder could not hitherto be 

 preserved. 



By the use of the above apparatus, however, M. Chamberland 

 proved two years ago that such milk will keep indefinitely, without 

 producing organisms, in contact with pure air. 



Many experiments claimed as favouring the spontaneous generation 

 theory are therefore explained in a very simple and rational way. 



Ijichens. 



Observations on Microgonidia.*— The Eev. J. M. Crombie, writ- 

 ing on the investigations of Dr. Minlts and Dr. Miiller | on what the 

 former calls microgonidia (or the minute corpuscules which, according 

 to him and Dr. Miiller, are in their evolution changed into gonidia, 

 and constitute the initial state of the latter), says that he does not 



* ' Grevillea,' vii. (1879) p. 143. t ^ee this Journal, ii. (1879) p. 311. 



