E. E. Atkin and A. Bacot 
525 
cultures from these tubes show that, while the bacteria infecting 9 and 11 are closely 
allied, probably the same species, the infection of 10 differs in that it shows a much 
less vigorously growing species. The interesting point is that, although the differ¬ 
ence in larval progress is shght, the divergence between the vigour of bacterial 
growth is extreme. 
After the \?)th day. 
Distilled water. Tubes 1 to 6. The only larva which emerged has made no 
progress and is now very feeble. 
Distilled water and Filtrate. The larvae in tubes 9, 10 and 11 are all of full size, 
but none of them have as yet pupated. In No. 12 three more eggs have hatched, 
none of the 6 larvae have as yet passed their first moult. 
Beef broth. In tube No. 13 aU the larvae have been killed by the vigour of the 
bacterial growth. In No. 14, 3 more eggs have hatched. In No. 15 the larvae are 
now either just approaching or past the second moult. This tube was passed on 
to a friend and kept at a lower temperature than the others—60° F. instead of 
75° F. In No. 16 another egg has hatched, neither of the two has made any pro¬ 
gress and one has died. In No. 17 one egg has hatched. In No. 18, 5 more eggs have 
hatched, but only the larva which emerged 12 days ago has made any progress and 
this one has not yet moulted. 
Beef broth and Filtrate. No. 20, one of the two larvae is dead; their progress 
since hatching is only just perceptible. 
No. 21, the larva has died without moulting. 
No. 22 (infected), 7 adults have been bred, 6 dd and 12; 1 fiving pupa remains. 
No. 23, 1 egg has hatched. 
No. 24, the larva has died without moulting. 
After the 2\st day. 
Distilled water. 1 to 6; the larva which emerged in tube 3 died in its first instar. 
Distilled water and Filtrate. In tubes 9 and 10 the larvae are marking time in 
their fourth instar. In No. 11, 2 dd have been bred, the remaining larvae, of full 
length, are marking time. In No. 12 the 6 larvae make scarcely perceptible pro¬ 
gress. 
Beef broth. In tubes Nos. 14, 16, 17 and 18 the larvae are making very slow pro¬ 
gress; a few are approaching, and one or two have passed their first moult. In 
tube No. 15, inoculated from No. 13 and passed on to a friend, the larvae made 
comparatively slow progress, presumably owing to the low temperature at which the 
tube was kept; apparently the vigour of the bacterial growth was the cause of their 
destniction. 
Beef broth and Filtrate. In tube No. 19 one egg uncapped, but the larva was 
either already dead or died immediately afterwards, as it failed to get clear of the 
eggshell. 
No. 20, 2 more eggs have hatched. The survivor of the first two larvae is now 
in its second instar. 
No. 22 (infected), another adult was reared (8 in all). 
No. 23, the larva from the only egg which hatched is now in its second instar. 
No. 24, another egg has hatched; the larva is now in its second instar. 
