Adjustment of colour in various jnqja', etc. 425 



2. Experiments upon the Vupje of Vanessa io. (Mabel 

 E. Notley, Florence A. Wright, and E. B. P.) 



The experiments of last year upon the struggle for 

 existence during the pupal period are now being repeated 

 in the case of Vanessa io. In this case all the pupse were 

 obtained at the outset of the investigation, and the results 

 as regards their colour susceptibility can now be given. 



We are greatly indebted to Mr. W. Farren of Cambridge, 

 and to Mr. H. W. Head of Scarborough, who sent us 

 numerous companies of larvae in excellent condition. Kind 

 help was also received from Mr. W. H. Harwood of 

 Colchester, and from Mr. A. E. Holdway of Newton Abbot. 



The lavvsd thus obtained were placed in a large number 

 of " light " and " dark " receptacles, the former being lined 

 with orange, yellow, or white paper (white opal glass was 

 used in the case of a few larvae), the latter with black 

 paper (a few were attached to the dull surface of perforated 

 zinc). All were placed in a strong light and only shielded 

 from the direct rays of the sun. A few were subjected to 

 conflictiug colours in one of the boxes described on pp. 418, 

 419. 



The results obtained are tabulated below (see p. 426), the 

 degrees of pupal colour being those described in Trans. Ent. 

 Soc. Lond. 1892, p. 398 ; the (l)s and (2)3 being the darkest 

 forms with the underlying green completely or very nearly 

 concealed by pigment which is blacker in (1), lighter in 

 (2) ; the (4)s and (o)s being distinct green forms very 

 bright and glittering in (5), duller and with more dark 

 pigment in (4) ; the (3)s intermediate. 



The pupse which were attached to the nettle-leaves, 

 leaf-stalks or stems are indicated by the letter 71, and 

 those found loose on the floor by the letter/. These facts 

 were not however recorded at the beginning of the experi- 

 ments so that more pup» were in reality found in these 

 positions in the companies received at first. The facts are 

 important inasmuch as the pupse on the floor were ad- 

 versely influenced in the experiments with light surround- 

 ings, the pupse on the nettles in the experiments with dark. 



The companies are tabulated separately below, but it 

 was not thought necessary to describe each separate re- 

 ceptacle, as this work is confirmatory. The numerous 

 receptacles in which the larvae of each company were 

 placed are grouped together as " light surroundings," and 

 " dark surroundings." 



