_ [From the Procerepines or THE Royat Society, Vou. 54.] 
“The Experimental Proof that the Colours of certain Lepido- 
pterous Larve are largely due to modified Plant Pigments 
derived from Food.” By Epwarp B. PouuTon, M.A,, F.R.S. 
Received May 12,—Read June 8, 1893. 
[PLATES 3 AND 4. ] 
In a paper printed in the ‘ Proceedings of the Royal Society’ for 
1885 (pp. 269—315), I brought forward many reasons for regarding 
certain elements of the colouring of Lepidopterous larve as modified 
chlorophyll derived from the food plant. For this altered pigment 
the name metachlorophyll was suggested (loc. cit., p.270). Many 
other observations, subsequently made, supported the same conclu- 
sion; but it was not until the summer of last year (1892) that I was 
able successfully to carry out the critical experiment, viz., selecting a 
species of larva which normally eats green leaves, to feed it from the 
ege upon parts of the plant from which all colouring matter is 
absent. 
This experiment was carried out in the following manner :— 
A captured female of Tryphaena pronuba laid many hundreds of 
egos in a chip box. The first larve began to appear September 7, 
1893. On this and the subsequent dates, the larve intended for the 
purposes of these experiments were arranged in three sets, fed re- 
spectively upon—(1) the yellow etiolated leaves from the central part 
of the heart of the cabbage, (2) the white mid-ribs of such leaves 
from which the yellow blade was carefully removed with scissors, 
(3) the deep green external leaves of the same plant. 
In all other essential respects the conditions of the three sets were 
the same. All were kept in the dark to prevent the change of the 
etiolin into chlorophyll. They were only exposed to light during the 
times necessary for comparison and feeding, and these are indicated 
below. A few were kept in glass cylinders standing on plates, the 
majority being confined in white earthenware pots covered at first 
with white muslin, but subsequently with glass sheets. Eventually 
all were kept in pots. 
It is clear that the only essential difference between the conditions 
of the sets was the fact that the food of the first contained etiolin but 
b 
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