ON INFECTIVITY, ETC., OF THE OYSTER. 665 
B. For 2. coli:-—1. Fermentation. Rate of gas formation variable, 
otherwise constant. 2. Jndol reaction. Reaction not constant. 3. Milk 
coagulation. Rate variable. Constant with us, with others not constant. 
4, Potassic iodide potato gelatine. Abundant growth. 5. Behaviour in 
gelatine. Diffusion very variable ; in many cases less rapid than B. typhosus. 
6. Motility. Very variable. 
II.—The Action of Sea-water upon the Growth of the B. typhosus. 
EXPERIMENT I. EXPERIMENT LY. 
No. of No. of 
Bacilli Bacilli 
At time of mixing . : - 29,250 | At time of mixing . : 5 130 
After 21 hours E : - 20,475 | After 6 hours : 3 : 41 
i> Ti. aes - 5 ; 9,945 ake DBE w ‘ é : 31 
” 71 ” . : . 9,360 ” 48 ” O 0 2 38 
cnt is ‘ é 5,850 Penk (aes 5 = . negative 
az ..,, big” Siewithy 260 A aoa rome Bas 1 
o) 340°, Oa FAS yt ihe), hagrsaies |g ces Na 0 
EXPERIMENT II. | EXPERIMENT VY. 
At time of mixine . : : 1,300 At time of mixing . : Be Re E240,0) 
After 21 a . ; ; : 1,105 Afcer 172 hours “ : 9,360 
ah Lath a Es 780 » 244 ,, eo Eras Se 325 
e wl is why are 650 - 
_ re 5 ‘ : 20K EXPERIMENT YI. 
St ae - 3 c 2 | At time of mixing . 2 : 325 
5 40! = P ‘ # O | After 172 hours ‘ i - 2 
EXPERIMENT III. EXPERIMENT VII. 
At time of mixing . % . 22.750 | At time of mixing . ; 3 325 
After 5 hours : , . 17,550 | After 504 hours (water kept at 
eas oe, Say Oo S' Cfo 1G) 2-74; 79 
Mg = bs Ap.) Pipa oe EXPERIMENT VIII. 
” ” . . . ’ 
» 247 4 i’ Auvtrds 455 | Attimeof mixing .. 325 
me OLb CC, F 5 ‘ 325 | After 504 hours : - : 0 
These results are fairly uniform. When a large number of bacilli are 
added to the water their presence may be demonstrated longer than in 
cases where smaller quantities are used. Fourteen days would appear to 
be the average duration in sea-water incubated at 35° C., whilst kept in 
the cold their presence was demonstrated on the twenty-first day. There 
appears to be no initial or subsequent multiplication of the bacilli. 
Between forty and seventy hours after infection there is less decrease than 
at other periods ; but there is no evidence of increase in numbers of the 
bacilli when grown in sea-water either when incubated or at ordinary 
temperatures. We do not think, however, that these experiments can be 
taken without reserve as an indication of what might take place in 
nature. 
II1.—The Bacteria present in the Alimentary Canal of the Oyster. 
This research has proved of very considerable utility in guarding us 
against errors in our subsequent infection experiments, and are of further 
