1918-19.] Life-History and Bionomics of Myzus ribis, Linn. 89 
sixth joint was rather greater (fig. 4). In dealing with sixty females of 
red blister stock, whose apterous parents had been transferred to green 
leaves ( = first generation on green leaf) the result was a little more con- 
clusive (fig. 3). The mode remains the same, but the curve has a tendency 
to form a “ shoulder ” falling near the mode of the green leaf curve. The 
second generation on green leaves were all apterous, and in the third 
generation only nine winged forms appeared. This number is too small 
for any conclusion to be drawn, though a tendency to shift the mode of 
the curve towards the mode of the green leaf type is apparent (fig. 5). 
A defect in these feeding experiments in 1918 was that I did not 
recognise the significance of the character of the food until the production 
of the winged forms was at its height. This occurred in the third and 
fourth generations, after which, for the rest of the summer, reproduction 
was limited to apterous forms which do not show the required characters. 
Next year it is hoped to carry out the feeding experiments from the first, 
and thus obtain more data on the subject. 
Table F. 
Table for comparison with Table D, to show the effect of rearing the red blister form on 
green leaves. Only the presence or absence of supplementary sensoria is considered 
here. For the position of the permanent sensoria, see Table E. 
1 
T otal 
Red Blister Type 
(many Sensoria). 
Green Leaf Type 
(few Sensoria). 
i 
j Undetermined. 
Number 
examined. 
Number. 
Per- 
cent. of 
Total. 
Number. 
Per- 
cent. of 
Total. 
Number. 
Per 
cent, of 
Total. 
Red blister form : trans- 
ferred in first instar 
to green leaf. 
47 
36 
76 
10 
21 
1 
•01 
Red blister form : first 
generation on green 
leaf. 
73 
56 
76 
17 
23 
Red blister form : third 
generation on green 
leaf. 
9 
9 
100 
1 
Kelly (18) recorded a difference in the ratio of Joint III to Joint IV of 
the antenna between forms of Aphis rumicis reared on opium poppy and 
nasturtium respectively ; but he did not ascertain whether this was due to 
the nature of the food, or to dealing with two different strains of aphides. 
The conclusion from his further researches among the progeny of poppy- 
fed females only, was that the progeny of somatically different mothers 
tend on the average to be alike, and that somatic variations in the par- 
