EXPLANATION OF PLATE XI. 



Fig. I. — Hygroscopic crystals of iridocytes obtained from NaOH 



solution. 

 Figs. 2,3, 4. — Crystals obtained from Sulphuric, Hydrochloric and 



Nitric acids respectively. 



(Fig. 4 Hygroscopic). 



Fig. 5. — Crystals obtained after treatment of HCl. sol. of irido- 

 cytes with HgCl.^. 

 6. — Crystals obtained after treating HCl. sol. of iridocytes 

 'with ZnCl.^. 

 Figs. 7, 8. — HCl and HNO^^ sol. of iridocytes treated with Picric 



acid. 

 Fig. q. — Silver derivation of oxyguanin. 



(Figs. 6-9 Hygroscopic). 



Fig. 10. — Lateral view of the tadpole {Microhyla ornata). 



,, II. — Dorsal view. 



,, 12. — Metallic band in situ. 



,, 13. — Colour and histological elements from dermis. 



a, b. black chromatophores and connective tissue corpuscles ; c. coloured 

 chromatophores, scales, granules and connective tissue corpuscles ; d. arg^enteo- 

 blarts ; e. argenteum and plate-like iridocytes ; f. phagocytes ; g. elements of the 

 dermis. 



Fig. 14. — Transverse section across the eye. 

 ,, 15. — Transverse section at about the fourth vertebra. 



Lettering in Figs, io — 12 & 14, 15. 



a. argenteum ; ac. air cavities ; b. brain ; cr. cranium ; d. diamond-shaped 

 mark; d.m. dorsal muscle; ep. epidermis free from chromatophores; ep'. with 

 chromatophores ; g. glandular area ; g'. gills ; /. iridocytes ; wz. black chromato- 

 phores. pe7'. peritoneum; ph. pharynx; .v. spuach ; f. transverse process; v. 

 vent; v'. ventral vessel ; v". vertebra. 



