Miscelhnieoux. 97 



On the Mechanism and Causes of the Clianges of Colour in the 

 Chameleon. By M. P. Bert. 



Tlie observatiuus and experiments which ai"e developed in the 

 memoir that I have the honour to hxy before the Academy may be 

 summed up in the following ])ropositions : — 



1. There exist, in the skin of the chameleon, contractile corpuscles 

 of diffei'ent colours, which are sometimes hidden in the depths of the 

 dermis and sometimes spread out at the surface in innumerable 

 ramifications, interlacing from one corpuscle to aiiother (Milne- 

 Edwards, Brueke, (J. Pouchet). 



We also find in it a superficial yellow pigment and a carulescent 

 layer (G. Pouchet), yellow by transmitted light, blue on an absor- 

 bent ground. 



2. The section of a mixed nerve has the result of giving to the 

 whole of the cutaneous region that it innervates a dark blackish 

 tint ; its excitation causes the same region to ac(iuire first a green, 

 then a yellow tint. 



This is the case also with a fragment of skin separated from the 

 body and then excited by electricitj' (Brueke). 



3. The section and the excitation of the spinal marrow^ produce 

 the same effects in tlie whole posterior region of the body. 



When the section is effected in the cervical region, the head and 

 the anterior part of the body are also blackened. The nerves which 

 run to the coloured corpuscles of these regions originate between the 

 third and the sixth dorsal vertebrae ; they follow the great sympa- 

 thetic nerve of the neck. 



4. After the section of the medulla the energetic excitation of a 

 mixed nerve induces, by refiex action, a slight lightening of the skin, 

 especially on the corresponding side. 



5. Semisection of the spinal marrow causes the blackening of the 

 corresponding side. 



6. After the ablation of the two cerebral hemispheres the animal 

 no longer spontaneously changes colour, but it changes as before 

 when it is excited. The same result follows the removal of the 

 optic tubercles, the cerebellum, or the commissure. 



But if the medulla oblonr/atahe cut transversely beyond the fourth 

 ventricle, the whole body becomes black, and no longer changes 

 colour. 



7. During sleep and anaesthesia, and after death, the whole body 

 becomes yellowish white. 



8. After the ablation of one cerebral hemisphere (an ablation tlie 

 consequence of which is the loss of the opposite eye), the corre- 

 sponding side changes colour much more rapidly than the opposite 

 side ; moreover, it remains always of a much darker tint. The 

 ablation of the sound eye does not restore the equilibrium. 



After the ablation of one eye the corresponding side remains much 



Ann. d: Mag. N. Fli'st, Her. 4. Vul. xvii. 7 



