THE RELATfON BETWEEN LIGHT AND PIGMENT-FORMATION. 583 



EXPLANATION OF PLATE 23, 



Illustrating- Professor Gamble's paper on " Tlie Relation 

 between Liglit and Pigraent-forrnation in Crenilabrus 

 and Hippolyte." 



Fig. 1. — Young Crenilabrus melops (x 5) in the dark-banded 

 phase induced by exposure to dark backgrounds. 



Fig. 2. — The green phase in the same fish induced by exposui-e to red 

 light transmitted by red weed, and also by exposure to backgrovmds 

 of red weed for one week. 



Fig. 3. — The reddish brown banded phase assumed by exposiire for 

 a week to light transmitted through green weed. The red colour is 

 a shade too pronounced in the figure. 



Fig. 4. — Young Hippolyte varians in the almost colom-less con- 

 dition in which it is taken among weeds when 4-5 mm. long, (x 24.) 

 These colom-less Hippolyte formed the starting-point for the experi- 

 ments i-ecorded in this papei*. 



Fig. 5. — The brilliant carmine colouring induced in Hippolyte by 

 exposiire to pure green light for three to four weeks. ( X 22.) Food- 

 plant, Ceramium. 



Fig. 6. — The green colouring induced in Hippolyte exposed to red 

 light for four weeks. Food-plant, fine green weed. 



Fig. 7. — The yellow colouring induced in some Hippolyte exposed 

 to red light for four weeks. Food-plant, Ceramium. 



Fig. 8. — Chromatophores from fig. 7, highly magnified. ( X 390.) 

 Fig. 9. — Chromatophores from fig. 6, highly magnified. ( X 390.) 

 Fig. 10. — Chromatophores from fig. 5. 



Fig. 11. — Chromatophores from Hippolyte exposed to white 

 i-eflected light for one month. 



