756 EEPOET — 1887. 



2. Farther Experiments v-pon the Colonr-relaiion bettueen Phytophagous 

 Larvae and their Surroundings. Bij E. B. POULTON. 



From the instance of the larval Smcrinthns ocellatus I have shown that certain 

 lepidoptercus larvae are susceptible to the influence of surrnunding colours, so that the 

 larvse themselves gain a corresponding appearance.' This larva varies from iright 

 yeliowish green to a dull whitish or bluish green, and either variety can he pro- 

 duced by the use of a food-plant with the appropriate colour on the undersides of 

 the leaves. Although the difference between the two varieties is very great when 

 they are placed together — so great in fact that I can readily distinguish three in- 

 termediate stages of variation between the e.vtremes — yet it is not nearly so well 

 marked as in the case of the green and brown varieties of many dimorphic larvse. 

 1 was therefore anxious to test one of these latter, and to ascertain whether either 

 variety can be produced at will by surrounding the larva with the appropriate 

 colour. Lord Walsingham had previously called my attention to the variable 

 larvse oi Humia craiaijata, some of which are brown, some green, while many are 

 intermediate. The larva exactly resembles the twigs of its food-plant, and always 

 rests upon the branches in a twiglike attitude ; and this habit rendered the species 

 very favourable for the purpose of this inquiry, which was conducted as follows. 

 A glass cylinder was provided with a black paper roof, a similar floor, and a small 

 quantity of the food-plant (hawthorn), the rest of the space being entirely filled 

 with dark twigs. Owing to their habit the larvse always rested upon these latter, 

 and after reaching maturity in two such cylinders forty dark varieties were pro- 

 duced. Three other cylinders were roofed and floored with green paper, and green 

 shoots bearing leaves were introduced as food, nothing brown being allowed inside 

 the cylinders. In these cylinders twenty-eight green varieties were produced. The 

 young larviE were obtained from the eggs of three captured females. After hatch- 

 ing, the larvse were thoroughly' mixed, and introduced into the cylinders whea 

 quite small. Some of the dark varieties were greenish and some of the green larvse 

 brownish ; but the greenest in the dark cylinders was browner than the brownest 

 in the green cylinders. The larvse were compared by placing the sets side by side 

 upon white paper, and the contrast between the larvse brought up in difl'erent sur- 

 roundings was very marked. In this case the larvse ate precisely tlie same kind of 

 leaf, so that it is clear that the eflects follow from the surrounding colours, and not 

 from the action of food. The instance recorded above is the best among the many 

 cases of adjustable colour-relation which are now known in lepidopterous larvae. 

 It is now extremely probable that all dimorphic species will show more or less of 

 this susceptibility to the colour of their environment. 



3. Some EeviarJis on the jRecen t liesearches of Zacharlas and Dr. Boveri upon 

 the Fecundation of the Ascnris Megalocephala. By Professor J. B. 

 Caenoy, of the University of Louvain. 



The first kinetic polar figure of this ascaris was given in the ' Prospectus ' of my 

 * Biologie Cellulaire ' in 1883. Since then I have published three notices on the 

 polar globules and the fecundation of the nematoids. At the end of the first article, 

 which treated of the Ascaris Megalocephala, I expressed a desire to see my 

 remarks commented on by some earnest and disinterested writer. O. Zacbarias and 

 Boveri have carried out this desire. 



I. Pular Globules. 



1. The remarks of Zacharias confirm my own on all important points : (a) There 

 is neither micropyle nor ' bouchon d'impregnation.' He admits with me (vide ' Pro- 

 spectus ') that the spermatozoid penetrates into the e^§ ly diyesting its membrane. 

 (Jb) The kinetic figures are opened and divided into two from their very commence- 

 ment ; therefore the ypsililorm figure of van Beneden does not exist. (<:•) The 

 figures of the two globules are identical, (r/j Out of eight nucleinic primitive 



' An account of these experiments will be found in Proc. Hoy. Foe. No. 237, 1885, 

 p. 269, and No. 243, 1886, p. 135. 



