o34 
Stegomyia fasciata 
Experiment XXV. 
Yeast and yeast extracts. 
Eggs sterilized by a slight variant of Method c were transferred by pipette into 
tubes containing 6 c.c. sterile distilled water. 
The number of eggs in each tube varied between about 25—50. 
h day 
an examination of tubes showed: 
No. 
1, 3 eggs hatched. 
Larvae dead. 
No. 
•2,3 
J » 
No. 
3, 5 
99 
*No. 
4, none hatched. 
No. 
5, 6 eggs hatched. 
Larvae dead. 
No. 
6, 2 
1 larva dead and I living. 
No. 
7, 3 
1 ,, ,, 2 ,, 
*No. 
8, none hatched. 
No. 
9, 1 egg hatched. 
Larva dead. 
No. 
10, 6 eggs hatched. 
5 larvae dead and 1 living. 
No. 
11, 10 
9 1 
^ 99 99 -^99 
No. 
12, 10 
Larvae dead. 
* The nuniber of eggs in these tubes was smaller than in the others, but more than 10. 
To tubes Nos. 1, 8, 3 and 7 -5 C.c. (= 1 in 12) of a sterile watery extract of yeast 
was added. 
To tubes Nos. 2, 9, 5 and 10 -5 c.c. (= 1 in 12) of sterile autolyzed yeast extract 
was added. 
To tubes Nos. 4, 6, 11, 12 a small mass of living yeast cells from a wort agar 
culture was added. 
After 10 minutes. 
Living yeasts (S. cerevisiae): 
Numbers of eggs had hatched in tubes 6—12 and 11, but only one in tube 
No. 4, but others followed almost immediately. 
Watery extract of brewers’ yeast: 
2 hatched in No. 3, a number in No. 1, none in No. 8, and only 1 in No. 7. 
Autolyzed extract of brewers’ yeast: 
Numbers hatched in tubes Nos. 2, 9, 5, and 10. 
After 45 minutes. 
Living S. cerevisiae: 
Numbers, probably most, of the eggs had hatched in Nos. 6, 12, and 11; a 
few in No. 4. The numbers were too large for accurate counting, but one 
got the impression that a smaller proportion of eggs have hatched in No. 4 
than in the other tubes. 
Autolyzed extract of brewers’ yeast: 
Hatching was general in tubes Nos. 2, 9, 10 and 5. 
Watery extract of brewers’ yeast: 
None had hatched in No. 8, only 2 in No. 3; a good proportion, probably 
one-third, had hatched in No. 1; only 3 in No. 7 out of a large number 
(probably quite 50 eggs). 
Tube No. 10 was infected from No. 4 to test the effect on larval growth. 
