39 
Table No. 31. — Feces and B. pi/ocyaneus, 3 per cent formalin, 37.2 per cent aldehyde. 
[* An anaerobic spore-bearing rod.] 
Time. 
Number of colonies 
grown. 
Days’ growth in broth tubes. 
1. 
2. 
3. 
4. 
5. 
6. 
7. 
8. 
9. 
10. 
Raw 
Innumerable, P 
-1-P 
At once 
Not counted 
-fP 
10 minutes 
273 
-f 
20 minutes 
26 
30 minutes 
6 
-f 
40 minutes 
4 
+ 
50 minutes 
3 
+ 
60 minutes 
+* 
90 minutes 
+ * 
120 minutes 
-f* 
Table No. 32. — Feces and B. pyocyaneus, 5 per cent formalin, 37.2 per cent aldehyde. 
[* An anaerobic spore-bearing rod.] 
Time. 
Number of colonies grown. 
Days’ growth in broth tubes. 
1. 
2. 
3. 
4. 
5. 
6. 
7. 
1 
9. 
10. 
Raw 
Innumerable, P 
-fP 
+ P 
At once. . 1 
Almost innumerable; not counted. .. 
73 
10 minutes 
-f 
20 minutes 
14 
-f 
-f 
30 minutes 
40 minutes 
6 
3 
50 minutes 
+* 
-f* 
60 minutes 
Table No. 33. — Feces and B. pyocyaneus, 10 per cent formalin, 37.2 per cent aldehyde. 
[* An anaerobic spore-bearing rod.] 
Time. 
Number of colonies grown. 
Days’ growth in broth tubes. 
1. 
2. 
3. 
4. 
5. 
6. 
7. 
8. 
9. 
10. 
Raw 
Innumerable, P 
-fP 
-1- 
At once 
Very few, “spreaders” 
10 minutes 
20 minutes 
30 minutes 
40 minutes 
6 
-b 
3 
-b 
+ 
1 
+* 
A look at the above tables shows that in all three dilutions the maxi- 
mum effect is exerted within the first ten minutes. In the 10 per cent 
dilution the great majority of the bacteria are killed almost immedi- 
ately; B. fiyocyaneus was killed in the 3 and 5 per cent dilutions in 
less than ten minutes and at once in the 10 per cent. 
The deodorant action of formalin is an important consideration when 
used for the disinfection of feces; the}^ are almost completel}^ deodorized 
at once by a 10 per cent solution; a 5 per cent solution does not com- 
pletely deodorize, but renders them almost inoffensive in a few minutes. 
There seems to be but little difference in the deodorant action of a 3 
and a 5 per cent solution. 
