ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
93 
Resistance of Bacteria of Swine Erysipelas to boiling, stewing, 
frying, salting, pickling, and smoking.* — From the experiments made 
by Dr. R. J. Petri vvitli bacteria of swine erysipelas, it seems that, though 
bouillon cultivations are destroyed in fifteen minutes at 52°, the de- 
struction of the organisms is not effected with certainty when a piece 
of swine’s flesh is boiled, stewed, or fried. Boiling, however, was 
successful provided the pieces were not heavier than one kilo and the 
boiling was kept up for about two and a half hours. There was some 
evidence that anaerobic cultivations were able to withstand a somewhat 
higher temperature. 
Pickling was equally unsatisfactory ; for virulent cultivations on 
silk threads soaked in 14 per cent, salt solution, to which 0’7 per 
cent, sugar and 0’4 per cent, saltpetre had been added, for a period 
of twenty days ; were not destroyed; but by using a brine containing 23 • 5 
per cent, of salt the bacteria were killed, a diminution in their virulence 
being noticed on the eleventh day ; and from the experiments altogether, 
it appears that pickled pork is quite as dangerous as fresh. 
The results of salting (16 grin, of saltpetre to the pound of salt) 
hams and flitches of bacon were, that after thirty days the meat was 
found to contain as many bacteria as before, and that thirteen out of 
eighteen mice inoculated from it died of the disease. The following 
result, which affords an interesting commentary on the difference between 
artificial and natural experiments, is worth noting. In default of any 
flesh of an animal dead of swine erysipelas, recourse was had to 
injecting healthy meat with virulent bouillon cultivations, not only in 
great quantity but at various depths. In twenty-eight days all the 
bacilli were dead. 
Two hams and flitches which had been salted for thirty days were 
then smoked for fourteen days. At the end of this time, eleven out 
of eighteen mice inoculated with pieces taken from the bacon died ; but 
by allowing these hams and flitches to hang, it was found that after 
167 days the bacilli could not be detected, hence it takes about half 
a year by this procedure to render swine’s flesh free from the disease. 
In what way the disease is set up is at present very uncertain, for 
the feeding experiments were practically all failures. 
Chemical Bacteriology of Sewage. f — Sir H. E. Roscoe and Mr. J. 
Lunt publish an abstract of their contributions to the chemical bac- 
teriology of sewage. With regard to all the organisms which they 
describe, the authors have determined the absorptive power for free 
oxygen when cultivated in a perfectly pure state, and they have deter- 
mined for which of them free oxygen is a necessity. They are able to 
show that anaerobic organisms associated with putrefaction, although 
able to grow in complete absence of oxygen, are able to absorb that gas 
rapidly, when it is present, and thus to prepare the conditions for their 
anaerobic growth. Some of them are incapable of liquefying gelatin 
without the presence of oxygen. Both in the case of aerobic and 
anaerobic organisms a very appreciable diminution of the liquefying 
* Arbeiten a. d. Kaiserl. Gesundheitsamte, vi. p. 266. See Centralbl. f. 
Bakteriol. u. Parasitenk,, x. (1891) pp. 135-7. 
f Proc. Roy. Soc. Lond., xlix. (1891) pp. 455-7. 
